Abstract: In view of safety problems such as premature separation of roof, advance of cutting line and rib fall of coal wall caused by being lack of initial support force of hydraulic support, a manual pressurization device for initial support force of hydraulic support was designed. The pressurization device is in parallel with hydraulic check valve of original support lifting hydraulic system, improves the initial support force through manual operation of pressurization under the premise that normal lift is not affected. AMESim modeling and simulation of the pressurization control circuit before and after applying the manual pressurization device were carried out. The simulation results show that the manual pressurization effect of the device is obvious. The field test result of pressurized situation for initial support force of ZY8500/21/45D type support on a coal mine working face shows that the manual pressurization device can significantly improve initial support force of the support and meet the coal mining demand.