The rotor and stator resistance, flux and load torque are easily affected during the operation of induction motor(IM), which goes against its high precision control, an online observation method is proposed. The mathematical model of IM is transformed to the standard nonlinear norm by differential homeomorphism transformation, and then a high gain observer(HGO) is designed, which does not require the system observable. The observation error can achieve any accuracy by adjusting of the gain of the observer. Simulation and experimental results show that the proposed method can achieve much higher accuracy and possess strong robustness to disturbance.