This paper analyzes the Extend Kalman Filter(EKF)based on Γ-1-type motor model, and on this basis, the sensor less rotor field-oriented control induction motor drive system is developed. EKF Analysis under Γ-1-type model simplifies the state matrix and reduces computation of EKF. Changes of motor parameters in EKF are attributed to the state noise. It makes the output values of EKF observe more accurate, and the performance of the vector control system also can be improved. Then, this paper establishes open-loop speed estimator that has a simple structure and is easy to be implemented. At last, the control system is achieved by DSP. Our experiments show the speed-sensor less induction motor drive system has a good static and dynamic performance.