The invention relates to a high-speed hydraulic motor. A front end cover is connected to a rear case by fixing bolts. The rear end of the rear case is provided with an oil inlet and an oil return portrespectively. A through hole is arranged at the center of the front end cover, and a shaft hole is arranged on one side of the through hole. A slot hole A and a slot hole B are respectively formed inthe rear case, the slot hole A intersects with the slot hole B, and the intersection overlaps are in communication with each other. An output gear shaft is rotatably arranged in the slot hole A, andthe other end of the output gear shaft is rotatably connected to the front end cover. A driving gear shaft is rotatably arranged in the slot hole B, and the other end of the driving gear shaft is rotatably connected to the shaft hole, and the output gear shaft meshes with the driving gear shaft. Gear slots of the driving gear shaft and the output gear shaft are respectively provided with oil drainage orifices. The high-speed hydraulic motor has the beneficial effects that the oil drainage orifices are arranged in the gear slots, so that the accumulated pressure generated by mesh of the high-speed rotation gears is effectively controlled; the oil drainage of an unloading groove on the top surface of the front end cover prevents the accumulated pressure in the case, and effectively reduces friction and takes away the heat to ensure the high-speed rotation of the gears.