After some major redesign works, initial improved Type 039A submarine (No.321) entered solution in April 2001, associated with another (No.322) in Dec 2001. .Since then more ships are entered solution because of the PLA Navy. Elimination from the stepped design for conning tower may be the primary artistic cue for recognition of 039A variation. A new layer of anechoic tile happens to be put on further lessen the noise. Weighed against Type 039, the underwater performance and noise degree of kind 039A submarine had been more satisfactory.