The structure characteristics of the piston pump cylinder copper bushing were introduced, which was simplified as the thick wall cylinder model for the theoretical calculation of the assembly over surplus quantity. On this basis, various stress nephograms were obtained by ABAQUS finite element analysis (FEA) under different over surplus quantities. Moreover aiming at impacting of the bushing cylinder with ring groove and without ring groove on assembly binding force, the FEA comparison was carried out, and the roles of the ring groove were analyzed. It provides reference for the structure design and over surplus quantity calculation of axial piston pump cylinder copper sleeve. 