The invention relates to the technical field of hydraulic motor pumps, in particular to a four-quadrant operation hydraulic motor pump. The four-quadrant operation hydraulic motor pump is characterized by comprising a main shaft, a motor rotor is pressed on the main shaft, the main shaft is supported and installed on a front shell and a rear end cover through a first bearing and a second bearing,the motor rotor is connected with the main shaft through a drum-shaped spline coupling, the motor rotor is fixed in the front shell through a partition disc, a motor stator, a motor end cover, a thirdsealing ring, a second sealing ring, a first sealing ring, a third screw and a third gasket, the motor stator is pressed on an inner hole of the rear shell, the rear end cover, a first end surface sealing gasket, the rear shell and a second end surface sealing gasket are fixed on the front shell through a fourth screw and a fourth gasket, a rear sealing cover and a rear sealing cover sealing ringare fixed on the rear end cover, a front sealing cover, a first front sealing cover sealing ring and a second front sealing cover sealing ring are fixed on the front shell. The four-quadrant operation hydraulic motor pump has the advantages of being mute, efficient, energy-saving, high in power density, good in speed regulation performance, compact in structure, free of external leakage and the like, and is particularly suitable for occasions with potential load characteristics and relatively frequent switching of forward and reverse rotation.