Abstract: The traditional liquid supply method for the hydraulic support of the working surface of Xinzhouyao Mine has a larger pressure fluctuation, larger displacement errors and larger flow pulses.The hydraulic support fluid supply system in coal mine is studied and optimized for the aforementioned practical problems.On the basis of analysis of factors causing pressure fluctuations and flow pulses of the hydraulic support, An intelligent hydraulic system of hydraulic support based on digital pressure relief valve is designed, which realizes the automatic matching of the actual hydraulic flow rate and the required flow rate, and alleviates the pressure impact caused by the opening and closing of the valve.The simulation results show that the digital pressure relief valve can effectively reduce the overshoot of the main valve and the impact on the system, and the pressure fluctuation is small.On-site installation and adjusting of hydraulic support at Xinzhou Yao Mine working face showed that the newly designed hydraulic support fluid supply system effectively reduced pressure fluctuations.During system recharge, the hydraulic support's fluid supply flow continued to increase, the flow pulse was small, and the operating speed was stable.