The invention relates to a method for positioning and assembling clearance fit parts of a motor axial assembly, and provides a random precision positioning method for the clearance fit of the motor axial assembly, which can solve the problem that in the assembly of axial parts with high requirements of position precision, the various clearance fit parts cannot ensure the positioning precision or have difficult operation. The random precision positioning method is characterized in that: relative positions among parts of a sleeve combination are fixed by matching with process threaded holes; then the sleeve combination is arranged in a motor shaft to form the motor assembly; the motor assembly is arranged in a shell so as to enable a gear to be engaged with a gear set in place, and the axialposition of the sleeve combination is positioned by special positioning screws; and finally, the various parts are connected reliably and arranged in the shell. The method has the advantages of simple process, convenient operation, safety, reliability and low manufacturing cost, and is particularly suitable for adjusting the axial position in place.