The invention discloses an improved invention of an oil hydraulic pump used as the power source of machining tools, which is characterized in that an oil outlet area (A) is controlled by an electromagnetic valve (2); an oil hydraulic area (B) is controlled by a motor; the oil hydraulic area (B) is divided into a low pressure area (C) and a high pressure area (D), wherein the low pressure area communicates with the high pressure area via an oil channel (11); the oil outlet area is provided with a drainback passage (19); and the drainback passage (19) forms a cycling oil passage with an oil cavity chamber (E) via a pipeline. As the oil hydraulic pump divides the oil hydraulic area into the low pressure area and the high pressure area, in the initial working stage of the oil hydraulic pump, arotating impeller can quickly transmit hydraulic oil in an oil chamber to the high pressure area; meanwhile, the piston acting in the high pressure area can transmit the hydraulic oil to a workpieceposition; therefore, the lack of oil in the oil passage when the piston acts in the initial working stage of the oil hydraulic pump is avoided, thus ensuring the service life of the workpiece; as themotor is arranged inside the pump body, the volume is reduced and the good portability is provided.