A hydraulic pump includes a pump body having a bearing hole and formed with a seal chamber at an end of the bearing hole and an oil groove therein, the oil groove ensuring hydraulic communication between the pump unit and the seal chamber, a pump cover attached to the pump body to define a concavity for accommodating a pump unit, and a drive shaft arranged through the bearing hole of the pump body. A bearing bush, which is arranged through the bearing hole of the pump body to support the drive shaft, includes bush lugs disposed in the axial direction of the bearing hole of the pump body. Two of the bush lugs disposed at both ends of the bearing bush have seams located circumferentially distant from each other.