The invention relates to a novel motor rotor structure comprising a punching sheet with the circular shape, and the inner circumference of the punching sheet is provided with positioning keys. The outer circumference of a rotor frame is provided with positioning key grooves matching with the positioning keys, and the punching sheet and the outer circumference of the rotor frame are in fit clearance; a plurality of inserting grooves allowing a magnetic steel to insert are arranged on the circumference of the punching sheet, the magnetic steel and the punching sheet are in fit clearance, and plastic rubber is injected in the clearance between two ends of the magnetic steel and the punching sheet. Since the punching sheet and the rotor frame are in fit clearance, the punching sheet and the rotor frame can be fixed tightly while the punching sheet is free of being pressed by a baffle; the magnetic steel and the punching sheet are in fit clearance, the plastic rubber is injected in the clearance between the magnetic steel and the punching sheet to fix the magnetic steel, the ends of the magnetic sheets are free of being shielded by the baffle, the magnetic steel can be applied to the motor rotor assembly directly, the occupied space is small, the rotor structure is simple, the space of the motor is saved effectively, material cost is saved, and the assembling efficiency of the rotor is improved.