Abstract: In order to improve the engineering applied performances of the high cutting shield type hydraulic powered support, the paper introduced the support fea tures of the double-telescopic leg.From the support lifting to constant resistance stage, a parameter physical model of the field type hydraulic powered support system was established.A simulation was conducted on the parameter model after the valuation.The results showed that under an external load role, according to the pre-set pr essure, the safety valve would be opened for overflow and the pressure in the middle cylinder would be varied with the pressure of the outer cylinder and would be kept in constant after the safety valve opened.Theoretically the paper analyzed the energy when the leg lowed down affected to the design of the hydraulic system of the hyd raulic powered support and the element parts.Meanwhile the theoretical basis of the two large flow safety valves, the necessity of the smooth rotary operation handle to the leg lowing down and the energy created from the high pressure emulsion after compressed affected to the reliability of the leg were verified and could provide the th eoretical references to the application and design of the hydraulic powered support.