The cushioning process of hydraulic cylinder belongs to unsteady flow of multiple relative motion, and also the performance of cushioning process will affect working characteristics of hydraulic cylinder. A three dimensional (3D) and timeaccurate Computational Fluid Dynamics (CFD) based on moving grid technique is used. The cushioning process of hydraulic cylinder was numerically simulated, and the influence of cushioning structure on cushioning characteristics was analyzed. The results show that the cushioning structure with cushioning ring forms a complicated vortex zone behind the cushioning ring, which will increase the obstruction effect of oil to the piston. Then the variable parameter analysis method is used to study the impact of different cushioning structure parameters on the cushioning characteristics. The analysis results are helpful for the optimal design of the hydraulic cylinders cushioning structure.