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By studying the performance principle of the hydraulic bumper, the overall characteristic model and the dynamic buffering process model of hydraulic bumper were built based on speciality analysis of its thin wall-orifice flow and spherical surface-slit flow. Then the curve of buffering force and piston distance, which expresses bumper characteristic, was obtained by simulation. The results showthat the static characteristic of the hydraulic bumper is only determined by the first characteristic of thin wall-orifice and the second characteristic of spherical surface-slit, and the dynamic characteristic is mainly related to the magnitude of shocking and the compressibility of oil.  