Speed-less sensor vector control system based on model reference adaptive system (MRAS) is studied to implement the closed-loop control of speed and field oriented control of induction motor in vector control system. Use voltage and current from asynchronous motor terminal estimate motor rotation speed. In asynchronous motor speed-less sensor vector control algorithm, use current model and voltage model to carry out magnetism linkage estimation, establish asynchronous motor rotor rotation speed diagnosis model based on MRAS method, then construct asynchronous motor speed-less sensor vector control simulation system in Matlab/Simulink. The simulation results show that this system has high dynamic and static performance and stability.