The embodiment of the invention provides a cylinder body, a hydraulic pump and a hydraulic motor, and relates to the field of hydraulic systems. The cylinder body is provided with a matching hole usedfor matching with a piston, the inner wall of the matching hole comprises a first inner wall, a transition inner wall and a second inner wall which are sequentially connected, and the hole diameter corresponding to the first inner wall is smaller than that corresponding to the second inner wall. The transition inner wall comprises a first guide face, and in the direction from the second inner wall to the first inner wall, the distance between the first guide face and the axis of the matching hole is gradually reduced so as to guide the piston to reciprocate between a cavity corresponding to the second inner wall and a cavity corresponding to the first inner wall. According to the cylinder body, the problem that the piston and the cylinder body are easily locked can be effectively solved.