Speed estimator is the key for the speed sensorless vector-controlled induction motor drive system. The precision of speed estimation directly determines the control result of the system. Applied MRAS method based on back electromotive force without pure integral to estimate speed, and introduced the vector control principle and speed estimation method. Firstly, made a simulation research with Matlab. Secondly, realized speed sensorless vector control in the experimental power system of motor testing station and in order to increase system robustness, system parameters used the motor thermal state parameters. The simulation of Matlab and the result of the engineering show that the method has a good speed estimator effect and system stability.