After some major redesign works, initial improved type 039A submarine (No.321) joined up with solution in April 2001, connected with another (No.322) in Dec 2001. .Since then more vessels are entered solution due to the PLA Navy. Elimination through stepped design for conning tower will be the primary revolutionary cue for recognition of 039A variation. A brand new layer of anechoic tile is placed on further lessen the noise. Weighed against Type 039, the underwater performance and sound level of type 039A submarine is at reality more satisfactory.