I have 3 rad grid in a page. While exporting all the 3 grids should be exported into the same excel file with different sheet.
anyone can help me in this.
Take a look at the Multiple worksheets in ExcelML code library thread. Telerik has provided a demo that shows how to create a multiple sheet ExcelML workbook that incorporates a RadGrid export.
I have not yet tried this, but it should be possible to export the contents from 3 separate RadGrids to individual worksheets by tapping into and modifying the code.