In this paper, experiments were carried out to study the friction and wear performance for the materials of piston and cylinder in a water hydraulic axial piston pump. The matching of 940 stainless steel circle with F102 engineering plastics block and 940 stainless steel circle with Al2O3 ceramic block were also studied. The wearing capacities were calculated by theoretical formulae based on the grinding crack widths. When pure water is used as hydraulic transmission medium, it is better to use ceramic with engineering plastics as matching materials for the piston and cylinder of water hydraulic axial piston pump. The experimental results have provided a theoretical basis for selecting the matching materials of piston and cylinder.