Aiming at the characteristic of Inter-turn short circuit (ITSC) fault of permanent magnet synchronous motor (PMSM), which is easily affected by load disturbance, this paper proposes a robust fault detection and location method for ITSC of PMSM based on voltage residual vector. Firstly, the change of motor back EMF caused by fault is analyzed by the motor voltage equation. Then the robust sliding mode observer (SMO) is used to predict the extended back EMF residual vector when the ITSC fault occurs to realize fault detection. Finally, the fault location is realized by generating a three-phase residual between the transformed three-phase back EMF and the reference back EMF. The simulation results show that this method can locate the ITSC fault and fault phase under sudden load and speed changes.