The invention discloses a high-pressure high-speed axial piston pump piston pair four-axis force testing device which is mainly composed of a swash plate shaft, a bearing assembly, a tested piston pair, an auxiliary piston pair, a four-axis force sensor, an oil lead piston, a piston base, a piston shoe press plate, a preloaded piston, a compression spring, a spring seat and the like. The ingenious lubrication structure of the ball head and hinge joint of the preloaded piston with adjustable pretension and the bearing assembly, the swash plate shaft in a dynamic balance balancing structure, the tested piston pair, the auxiliary piston pair, the oil lead piston and the four-axis force sensor with a center through hole structure are designed. The tested piston pair and the auxiliary piston pair are symmetrically arranged. The ball head structure of different sizes on both ends and the ball hinge pair of the oil lead piston are connected. Interference factors on the tested piston pair are eliminated. Three-dimensional direction action force and axial torque of a high-pressure high-speed piston pair are measured. The device has the advantages of simple and reliable overall structure, easy part replacing and low machining and detection cost.