[8] simulated the single pumping piston torque on the swash plate based on a hydraulic-mechanical co-simulation model and reduced the flow ripple rates through integration and optimization. [PERSON] et al. [9] established a flexible multi-body dynamic model of an axial piston pump and found that the main noise source is the excitation force of the swash plate on the housing. The actuator piston in the variable displacement mechanism constitutes another main part of the torque on the swash plate. [PERSON] et al. [10] conducted a study on the sensitivity of the outlet pressure control to certain parameters within the pump system, and the total torque on yoke due to the force of pumping pistons and bias pistons was given. However, the high-frequency swash plate oscillation was not discussed. [PERSON] et al. [11] derived the equations for the actuator forces applied on the swash plate, which could be used to obtain the control and containment requirements for any steady-state operating condition of any pump with similar swash plate design. The control valve and actuator were modeled by [PERSON] to investigate the oscillations on the swash plate [12]. He found out that the oscillations of the swash plate become bigger at small speeds, small setting angles, and larger pressures. [PERSON] [13] built a simulation model to investigate swash plate oscillation in a variable displacement floating cup pump and came to similar conclusions to [PERSON]. [PERSON] et al. [14] measured the low-frequency variation in the swash plate control torque when the swash plate starts moving at the vicinity of the set pressure zone, and the simulated torque shows similarities with the experimental result, except for at the low flow zone. [PERSON] et al. [15; 16] developed a multi-body dynamic model without the consideration of fluid to study the bearing forces, control piston force, swash plate motion, and torque ripple. [PERSON] summarized the variation of the angular oscillations of the swash plate about the axis perpendicular to the driveshaft. Other scholars have also studied the control characteristics of the piston pump system. They analyzed the stability of the load-sensing (LS) controlled variable displacement pump system and found that the LS systems are prone to oscillation or even unstable behavior, because the load dynamics and the pump dynamics become inherently heavily coupled through an LS mechanism [17; 18; 19]. [PERSON] et al. [20] used an electronic angle sensor and an acceleration sensor to measure the dynamic state of the swash plate of a modified high-bandwidth pump control system. They achieved adjustable swash plate vibration reduction at the desired frequency by the active vibration control. In the studies on the electro-hydraulically controlled variable displacement pumps [21; 22; 23; 24], the swash plate angle of the piston pump was measured and controlled, but no obvious oscillatory behavior of the swash plate angle was noticed. The displacement angle was also measured with a Hall-effect sensor in a hardware-in-the-loop simulation test rig by [PERSON] et al. ; he used a pole placement approach combined with a lead-compensator controller architecture to control the swash plate angle [25; 26]. [PERSON] et al. [27] designed a fault diagnosis method for an intelligent hydraulic pump system using a nonlinear unknown input observer based on the output pressure and swash plate angle signals. In previous studies, although some researches modeled both the variable displacement mechanism and the piston-slipper units, they did not analyze the influence of the structure parameters on the swash plate dynamics in the piston pump. In the high-speed piston pump, the vibration of the swash plate could lead to serious damage of the pump. Therefore, this paper presents an improved model for investigating the dynamic performance of the swash plate at a high frequency, analyzing and optimizing its structure parameters.