A newly developed approach to identify the mechanical speed of an induction motor based on neural network technique is described.The back-propagation neural network technique is used to provide a real time adaptive estimation of the motor speed.The error between the desired state varible and the actural one is back-propagated to adjust the rotor speed.So that the actural state varible will coincide with the desired one.The theoretical analysis as well as the simulation results to verify the effectiveness of the new method are described in this paper.