In order to improve the shift performance of the tractor hydraulic power-split CVT, the influence factors and the parameters matching were studied based on the method of both simulation and experiments. First of all, the model of clutch axial force and the model of transmission system were built based on the experiments on shift pressure and piston displacement. The model was proved to be correct and effective with eight groups of experimental verification under different test conditions. Then, the influence factors were divided into three groups, i.e., the external factors, the designing factors and the controllable factors, and each influence factor on shift performance was simulated and analyzed. Finally, the interactive effects among these factors on shift performance were studied and the optimal parameters were acquired. The research results showed that there was no significant effect of the pipeline volume of swash plate axial piston units on shift performance. The effect of engine speed on shift performance was influenced by the displacement of variable displacement pump. The shift performance would be improved with the increase of clutch oil charge flow and shift timing under the prerequisite of constant output speed condition. The effects of clutch oil charge pressure, load torque and inertia on shift performance were not robustness. The research is helpful to improve the dynamic characteristics of the hydraulic power-split CVT and it is useful to develop the control unit.