A motor oil pump assembly includes: an oil pump component is supported on an end cover of a motor component, and an upper end cover of the oil pump component has an end cover cavity that runs through the upper end cover and in communication with a high-pressure cavity of the oil pump component; an inner sound insulation enclosure encloses the oil pump component and is in communication with a low-pressure cavity of 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; and a pre-tightening buffering component includes a piston and an elastic member, the piston fits in with the end cover cavity to isolate the high-pressure cavity from the inner sound insulation cavity, and the elastic member is elastically sandwiched between the piston and the inner sound insulation enclosure.