A speed identification approach based on the back electromotive force (EMF) was proposed for the induction motor vector control system using cascaded inverter. The method used the backEMF as the system model output to construct the model reference adaptive system (MRAS). MRAS used a reference model and adjustable model parallel structure to achieve speed identification. The problems caused by pure integral part were eliminated. The proposed method was applied to the induction motor vector control system. The simulation and experiment systems were implemented. Simulation and experiment results showed that the method was easy to implement and could accurately estimate the motor speed.