The present disclosure discloses a motor oil pump assembly, a steering system, and a vehicle. The motor oil pump assembly includes: a motor component; an oil pump component; an inner sound insulation enclosure, where the inner sound insulation enclosure encloses the oil pump component, and the inner sound insulation enclosure and the oil pump component define an inner sound insulation cavity filled with low-pressure oil, the inner sound insulation cavity is in communication with a low-pressure cavity of the oil pump component, and the inner sound insulation enclosure is provided with a sound insulation enclosure cavity; and a pre-tightening buffering component, where the pre-tightening buffering component includes a piston and an elastic member, the piston fits in with the sound insulation enclosure cavity and presses against an upper end cover of the oil pump component, and the elastic member is used to provide a pre-tightening force for tightly pressing the upper end cover, where the sound insulation enclosure cavity is in communication with a high-pressure cavity of the oil pump component, so that the piston tightly presses the upper end cover under the action of oil pressure.