Abstract: Permanent Magnet Synchronous Motor(PMSM) has received more and more attention in the field of rail transportation due to its many advantages. PMSM usually enters the square wave condition at high speed range. In order to solve the problem that the motor voltage could not be completely adjusted under square wave condition, a control strategy based on a single d-axis current regulator to adjust the q-axis voltage(SDCR-VQ) was proposed. This method could be applied to the control of any form of permanent magnet motor in the full field weakening area. By establishing a small signal model of this method, its stability and dynamic performance were analyzed. Based on this method, aiming at the problem that the motor parameters of the permanent magnet motor may change during operation, the influence of the inaccurate motor parameters was analyzed and a multi-parameter online compensation strategy was proposed. Finally, simulations and experiments verified the effectiveness of the proposed control strategy and parameter compensation method under square wave condition.