It needs to be stamped.

When issuing a bank confirmation letter, the replying party shall sign the official seal of the unit when the data proves to be correct, the data does not match, and matters that require explanation according to the actual situation, and shall be signed or stamped by the handling personnel.

The seal that needs to be affixed is the signature reserved when the company opens a bank account or the signature that the company and the bank agree to affix when handling correspondence business. It is best to communicate and confirm with the bank in advance to avoid If the seal does not match, reissue the letter.