Abstract: According to the actual performances of the leg operation in the powered support,a dynamic features analysis model of the leg in the powered support w as established under the impact load role.The finite element and smooth grains fluid dynamics method were applied to solve the fluid-solid coupling,high fluid deformati on and other problems of the leg in the powered support.The dynamic responses numerical simulation of the leg under the impact load role was realized.The cylinder st ress distribution of the leg,the max recession value of the piston and the fluid pressure field distribution under the impact load were obtained,including the max impact f orce and other key technical parameters of the full impact process to the foundation.The solid and fluid spring coupling theory and the energy method were applied to d erive the equivalent rigidity of the leg solid and fluid coupling system and the impact dynamic load parameters of the leg.Thus theoretically,the dynamic features of the p owered support leg under the impact load role and the max impact force to the foundation were analyzed.In comparison with the theoretic analysis results and the nume rical simulation results,there was a consistency within the error scope.The study results could provide related reference data to the development of the anti impact perfo rmances test device of the powered support leg.