By studying the old surface grinder which spare parts are difficult to change and the energy leakage points are many, a relatively simple way was used to transform the hydraulic system, to reduce energy consumption and improve the interchangeablity of spare parts. At the same time, a dynamic simulation to the transformationable system was made by using hydraulic system simulation software AMESim, getting the simulation curves of hydraulic system pressure and speed in working condition. The curves prove the tansformated hydraulic system is feasible.