Hello, Kaan,         

According to the provided information, it is not very clear how exactly you import Excel data in RadGridView. Could you please elaborate?

I suppose that you set the DataSource collection for RadGridView. Note that RadGridView can auto-generate its columns considering the available fields in the applied DataSource or you can manually add the columns you want to have in the grid. This can be controlled by the AutoGenerateColumns property. Additional information is available in the following help article: https://docs.telerik.com/devtools/winforms/controls/gridview/columns/generating-columns

Since you have submitted a feature request in our public feedback portal, could you please provide additional information what is the exact behavior that you are expecting to obtain? Thus, we would get better understanding of the precise case and assist you further.

Thank you in advance for your cooperation. I am looking forward to your reply.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik