The present invention discloses a motor protection device and a method which are applicable to a motor. The motor protection device consists of a detection unit for detecting motor operation state and the outputting a detection signal, a datum unit for producing a variable datum signal, a distinguishing unit for comparing the detection signal and the variable datum signal and distinguishing whether the motor is abnormal or not, and a protection unit for obtaining the result of the distinguishing unit and limiting the motor drive current when the motor is abnormal. The present invention is characterized in that the datum unit adjusts the variable datum signal according to a rotation detection signal (R.D.signal,Rotation Detection signal) of the motor so as to distinguish whether the motor is abnormal or not by synchronizing the motor rotation detection signal and the detection signal, thus achieving the dual-guarantee effect of the motor when the motor is abnormal.