The horizontal type double-sided double work positions modular machine tool is used for milling the two ends of automobile front axle and drilling main pin hole.It has high machining accuracy and high processing efficiency.The hydraulic system can finish workpiece clamping,assisting clamping and moving-workbench moving.By analyzing the main working process of the modular machine tool hydraulic system,it was discovered that the system heating and the hydraulic cylinder creeping could mainly effect the hydraulic system stability.After analyzing the reasons,the solutions were brought out.The solutions can forcefully guarantee the stability of the modular machine tool.