Abstract: Taking CST soft-starting device used for conveyors of Jining No.3 coal mine as an example, the paper indicated that slack routine maintenance is the main cause of mine-used CST soft-starting device's faults. Based on the hydraulic principle of CST soft-starting device's control system and manufacture's maintenance requirements, the paper analyzed importance of replacing hydraulic oil and filter element and daily cleaning. Finally, it pointed out that mine enterprises should do optimal routine maintenance of CST soft-starting device with less cost according to actual situation.