Abstract: According to the large maintenances and high starting impact problems existed in the major hydraulic coupling and double speed motor driving applied t 0 the 3.3 kV powered scraper conveyor, the high voltage and high power thyristor voltage contral technology, computer technology and the communication technology w as applied to research and develop the 3.3 kV QJR-350/3.3S soft starter.The paper stated the work principle of the 3.3 kV soft starter, including the main technical para meters and technical features.The paper analyzed the actual application conditions. The results showed that the soft starter would have a smooth and steady starting, s . mall impact, operation convenient and high flexibility and could meet the application of the 3.3 kV powered scraper conveyor.