The axial flow fan is a kind of turbomachinery equipment to provide compressed gas and the stator blade adjusting mechanism is the key to the whole system. Taking the stator blade adjustment electrohydraulic servo system as the research object, the traditional hydraulic servo system is vulnerable to oil pollution, high failure rate and low energy conversion efficiency. To solve the abovementioned problems, the Direct drive volume control hydraulic system for stator blade adjustment is designed, the hydraulic power source of the system is composed of servo motor and bidirectional quantitative pump. The working principle of this system is analyzed, the simulation model of hydraulic system is built and solved. The results show that the new system has higher energy efficiency, the structure is more compact, the machine power is smaller and the control is more automatic and intelligent as compared to the traditional one.