Hi Mahesh1986,
Check this example. Now please take its reference and correct your code.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<link rel="stylesheet" href="https://cdn.datatables.net/1.10.12/css/jquery.dataTables.min.css" />
<link rel="stylesheet" href="https://cdn.datatables.net/buttons/1.2.2/css/buttons.dataTables.min.css" />
<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.3.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/1.10.12/js/jquery.dataTables.min.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/buttons/1.2.2/js/dataTables.buttons.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/2.5.0/jszip.min.js"></script>
<script type="text/javascript" src="https://cdn.rawgit.com/bpampuch/pdfmake/0.1.18/build/pdfmake.min.js"></script>
<script type="text/javascript" src="https://cdn.rawgit.com/bpampuch/pdfmake/0.1.18/build/vfs_fonts.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/buttons/1.2.2/js/buttons.html5.min.js"></script>
<script type="text/javascript">
$(document).ready(function () {
$('#example').DataTable({
dom: 'Bfrtip',
buttons: [{
extend: 'excel',
text: 'Excel',
className: 'exportExcel',
filename: 'Test_Excel',
exportOptions: { modifier: { page: 'all'} }
},
{
extend: 'csv',
text: 'CSV',
className: 'exportExcel',
filename: 'Test_Csv',
exportOptions: { modifier: { page: 'all'} }
},
{
extend: 'pdf',
text: 'PDF',
className: 'exportExcel',
filename: 'Test_Pdf',
exportOptions: { modifier: { page: 'all'} }
}]
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<table id="example" class="display nowrap">
<thead>
<tr>
<th>Id</th>
<th>Name</th>
<th>Country</th>
</tr>
</thead>
<tfoot>
<tr>
<th>Id</th>
<th>Name</th>
<th>Country</th>
</tr>
</tfoot>
<tbody>
<tr>
<td>1</td>
<td>Mudassar Khan</td>
<td>India</td>
</tr>
<tr>
<td>2</td>
<td>Maria</td>
<td>Austria</td>
</tr>
<tr>
<td>3</td>
<td>Ana Trujillo</td>
<td>France</td>
</tr>
<tr>
<td>4</td>
<td>Antonio Moreno</td>
<td>Brazil</td>
</tr>
<tr>
<td>5</td>
<td>Thomas Hardy</td>
<td>Ireland</td>
</tr>
<tr>
<td>6</td>
<td>Christina Berglund</td>
<td>Italy</td>
</tr>
<tr>
<td>7</td>
<td>Hanna Moos</td>
<td>Finland</td>
</tr>
<tr>
<td>8</td>
<td>Laurence Lebihan</td>
<td>Finland</td>
</tr>
<tr>
<td>9</td>
<td>Elizabeth Lincoln</td>
<td>Canada</td>
</tr>
<tr>
<td>10</td>
<td>Victoria Ashworth</td>
<td>UK</td>
</tr>
</tbody>
</table>
</div>
</form>
</body>
</html>
Demo
If you want custom button refer below link.
