The feasibility of sliding mode variable structure control in coal mine mechanical hydraulic system was discussed. The sliding mode controller was designed and calculated, and the control performance of sliding mode variable structure control was analyzed by simulation. The application feasibility of sliding mode control in coal machine was verified by experiments. Sliding mode variable structure control can realize high-precision control of coal engine action cylinder, with small chattering and overshoot, and has good robustness to parameter uncertainty, but it puts forward higher requirements for coal engine oil purity and sensor quality.