An improved sliding mode control speed regulator was proposed for permanent magnet linear synchronous motor (PMLSM) direct thrust control system which had the defects such as large overshoot, poor load disturbance resistance, slow response and so on. The weighted integral gain reaching law was combined with the constant speed reaching law to reduce the increase of the switching gain when the system was not in the sliding mode phase. The simulation compared with PI controller showed that the response time of the system speed under load change was shortened, and the antidisturbance ability was improved obviously when the improved sliding mode speed controller was applied to the PMLSM direct thrust control system.