Many methods have been used to detect the motor speed. All of these methods are based on the parameter equation of motor and the detection results are influenced by parameters of induction motor more or less. The research of Speed Measurement method without of Motor parameters effect is very significant. Based on the harmonic generated in the air gap magnetic field by the stator core on the alveolar surface, directly by the analysis and testing of stator current harmonic, the rotor speed is detected which is proportional to the speed of frequency components. Experiment results show that this method is good, and the accuracy achieve a desired effect in real time.