Based on selfadaptive identification theory, an easily realized reconfigurable method for the control system was presented, including a full state observer used to acquire the load torque state and a selfadaptive module used to lead the convergence of reconfigurable system. By taking the electromagnetic torque and the load torque observing state as input of reconfigurable system, the moment of inertia could be acquired when the system converges. The feasibility and efficiency of the proposed method had been verified by the simulation results, different inertia values set in the model can be identified accurately.