In OpenERP first, create existing module and then inherits the account.invoice object in your own module and also create report file in your own module.

Follow these step given belowas

Step1- First create module like, test then create file in your module like, test.py and inherits the account.invoice object in your test.py file and pass this file in the __init__.py file.

Using this code given below

import time
from openerp.report import report_sxw
from openerp.osv import osv

Step2- Then create another file like: test.xml file in your own module and pass this file in your __openerp__.py file.

Using this file given below

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>  
      <report
            id="report_account_invoice_new"
            string="Invoice"
            model="account.invoice"
            report_type="qweb-pdf"
            name="test.account_invoice"
            file="test_invoice"
        />
</data>
</openerp>

Step3- Then create another file like test_invoice.xml file. In this file we create templates of report and design.

Using this code given below

<openerp>
    <data>
        <template id="invoices_reports">
            <t t-call="report.external_layout">
                <div class="page">
                    <div>
                        <div align="center" style="font-size: 20px;">INVOICE</div>
                        <br/>
                        <div align="center" style="font-size: 15px;"><span t-esc="o.payment_ids.journal_id.name"/></div>
                        <div class="row">
                            <div class="col-xs-6">
                                <div style="font-size: 15px;">Invoice NO.<span t-field="o.number"/></div>
                            </div>
                            <div class="col-xs-5 col-xs-offset-1" >
                                <div  style="font-size: 15px; margin-left: 1.0cm">Date: <span t-field="o.date_invoice"/></div>
                            </div>
                        </div>
                    </div>
                    <br/>
                    <br/>
                    <table class="table table-condensed" style="border: 1px solid black">
                        <thead>
                            <tr style="border: 1px solid black">
                                <th style="border: 1px solid black; text-align: center; width : 2.0cm">SNo.</th>
                                <th style="border: 1px solid black; text-align: center; width : 2.0cm">Code</th>
                                <th style="border: 1px solid black; text-align: center; width : 9.0cm">Descirption</th>
                                <th style="border: 1px solid black; text-align: center; width : 2.0cm">Qty</th>
                                <th style="border: 1px solid black; text-align: center; width : 3.0cm">Unit / Pack size</th>
                                <th style="border: 1px solid black; text-align: center; width : 3.0cm">Amount</th>
                            </tr>
                        </thead>
                        <tbody class="invoice_tbody">
                        <tr t-foreach="o.invoice_line" t-as="l">
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center" >                               <span t-esc="l_index+1"/>
                            </td>
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center">                              <span t-field="l.product_id.default_code"/>
                            </td>
                            <td  style="border: 1px solid black; width : 9.0cm; text-align: center">                               <span t-field="l.name"/>
                            </td>
                            <td  style="border: 1px solid black; width : 2.0cm; text-align: center">
                                <span t-field="l.quantity"/>
                            </td>
                            <td  style="border: 1px solid black; width : 2.0cm; text-align: center">                                <span t-field="l.qty_char"/>
                            </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">                                <span t-field="l.price_unit"/>
                            </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">                              <span t-field="l.price_subtotal"/>
                            </td>
                        </tr>
                        <tr style="height: 0.8cm">
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center" >
                            </td>
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 9.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 2.0cm; text-align: center">
                           </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">
                           </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">
                            </td>
                        </tr>
                        <tr style="height: 0.8cm">
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center" >
                            </td>
                            <td style="border: 1px solid black; width : 2.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 9.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 9.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 2.0cm; text-align: center">
                            </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">

                            </td>
                            <td  style="border: 1px solid black; width : 3.0cm; text-align: center">
                            </td>
                        </tr>
                        </tbody>
                    </table>
                        <div class="col-xs-6">
                            <table class="table table-condensed" style="border: 1px solid white;">
                                <tr style="border: 1px solid black">
                                    <td style="border: 1px solid white; width : 2.0cm">
                                        <strong>Amount Paid</strong></td>
                                    <td style="border: 1px solid white; width : 2.0cm">
                                        <span t-feild="o.amount_total"/>
                                    </td>
                                </tr>
                                <tr style="border: 1px solid white;">
                                    <td style="border: 1px solid white;; width : 2.0cm">
                                        <strong>Payment Detail</strong></td>
                                    <td style="border: 1px solid white; width : 2.0cm">
                                        <span t-field="o.payment_term"/>
                                    </td>
                                </tr>
                                <tr style="border: 1px solid white;">
                                    <td style="border: 1px solid white; width : 2.0cm;">
                                        <strong>Balance</strong></td>
                                    <td style="border: 1px solid white; width : 2.0cm;">
                                        <span t-field="o.residual"/>
                                    </td>
                                </tr>
                            </table>
                        </div>
                        <div class="col-xs-5 col-xs-offset-1" >
                            <table class="table table-condensed" style="border: 1px solid black; margin-left: 0.5cm">
                                <tr style="border: 1px solid black">
                                    <td style="border: 1px solid black; width : 1.0cm; text-align: center"><strong>Total</strong></td>
                                    <td  style="border: 1px solid black; width : 1.0cm; text-align: center">
                                        <span t-field="o.amount_untaxed" t-field-options='{"widget": "monetary", "display_currency": "o.currency_id"}'/>
                                    </td>
                                </tr>
                                <tr style="border: 1px solid black">
                                    <td style="border: 1px solid black; width : 1.0cm; text-align: center">Discount</td>
                                    <td style="border: 1px solid black; width : 1.0cm; text-align: center">
                                        <span t-field="o.amount_tax" t-field-options='{"widget": "monetary", "display_currency": "o.currency_id"}'/>
                                    </td>
                                </tr>
                                <tr style="border: 1px solid black">
                                    <td style="border: 1px solid black; width : 1.0cm; text-align: center"><strong>Total Bill Amount</strong></td>
                                    <td style="border: 1px solid black; width : 1.0cm; text-align: center">
                                         <span t-esc="o.amount_untaxed*o.discount/100" t-field-options='{"widget": "monetary", "display_currency": "o.currency_id"}'/>
                                    </td>
                                </tr>
                            </table>
                        </div>
                </div>
            </t>
        </template>
        <template id="external_layout_footer" inherit_id="report.external_layout_footer">
        </template>
        <template id="report_header_new" inherit_id="report.external_layout_header">
            <xpath expr="//div[@class='header']" position="replace"/>
        </template>
        <template id="report_invoices">
            <t t-call="report.html_container">
                <t t-foreach="doc_ids" t-as="doc_id">
                    <t t-raw="translate_doc(doc_id, doc_model, 'partner_id.lang', 'test.invoices_reports')"/>
                </t>
            </t>
        </template>
    </data>
</openerp>