The invention discloses a pump body of a lubricating pump, comprising a pump shaft support hole, a rotor cavity and a big end surface. The big end surface is used for mounting the pump cover and recesses inwards along the radial direction of the rotor cavity to form stepped-holes. The invention also discloses a pump cover of the lubricating pump, comprising the pump body and the pump cover. The pump cover is embedded into the stepped-holes and matched with the stepped-holes in transition. The invention also discloses a lubricating pump, comprising the pump body, the pump cover, an inner rotor, an outer rotor and a pump shaft. The edge of the pump cover is matched with the stepped-holes in transition and seals the rotor cavity, the pump shaft passes through the pump shaft support hole, theend part of the pump shaft extends into the support hole at the end part of the pump shaft, the pump shaft is also internally provided with an overflow circumfluence hole which extends from one end of the pump shaft far from the pump cover along the radial direction of the pump shaft, and the axial length of the overflow circumfluence hole is shorter than that of the pump shaft. The invention improves the locating accuracy and the locating strength of the pump cover, simplifies the assembling flow, improves the working efficiency, avoids the engine oil leakage phenomenon, and has simple and compact structure and easy implementation.