How can I insert bulk data from an Excel file to Ms Access data base using OLEDB connection without using loops. I'm using OLEDB connection in a C# windows application?

There is no bulk insert method for MS Access in the meaning of SqlBulkCopy[^] for Sql-Server.

Which means the answer to your question is: you can not.

If you need performance, MS Access is not the right choice. If you want to stick with MS Access, you will have to use loops. If you're willing to use DAO instead of OleDB you probably can gain some significant performance increase though, as this link suggests:
http://stackoverflow.com/questions/7070011/writing-large-number-of-records-bulk-insert-to-access-in-net-c[^]