After some major redesign works, initial improved kind 039A submarine (No.321) joined solution in April 2001, associated with another (No.322) in Dec 2001. .Since then more vessels are entered solution because of the PLA Navy. Elimination through the stepped design for conning tower could be the main innovative cue for recognition of 039A variation. A new layer of anechoic tile is placed on further lessen the noise. Weighed against Type 039, the underwater performance and sound degree of type 039A submarine was at reality more satisfactory.