The variable displacement bent piston pump with rotary valve plate (hereinafter referred to bent piston pump) is the core hydraulic power element of servo system.Bent piston pump is characterized by using rotary valve plate to realize the constant pressure variable displacement function with simple structure.Its structural form and operation principle were introduced and analyzed.With the mathematical model derived,an AMESim simulation model of the bent piston pump was constructed.The dynamic and static performances were simulated and analyzed.The constructed model can provide some theoretical basis and rapid design method for the optimal parametric design of similar piston pump.