Hi Somdeb,
Thank you for contacting Syncfusion support.
HTML to PDF converter internally make use of QtWebKit rendering engine for converting HTML to PDF. WebKit rendering engine will repeat the table header when the table has thead tag and the table gets paginated between the PDF pages. So, please make sure that the table has the thead tag for the table header and the table is paginated between the PDF pages.
If still you are getting the same issue, kindly share us the input HTML file and code snippet to reproduce it from our end. It will be helpful for us to analyze and assist you further.
Regards,
Prakash V