The forging manipulator is a key equipment for manufacturing important equipment in nuclear power,thermal power and rail transition. According to the requirements of high speed,high precision and reliability for the forging manipulator,the function of hydraulic system is analyzed and the circuit of hydraulic system is designed on the basis of function analysis. The hydraulic control system circuit of the forging manipulator consists of clamp system,raising and pitching system,horizontal migration system,buffer system,gantry travelling system and clamp rotation system. The hydraulic pumping station adopts the average flow method to realize the energy saving. Simulation and analysis research on the key control performance(celerity,accuracy and startup performance) and reliability of the hydraulic system is carried out on the basis of mathematical model. The results show that both control performance and reliability of the hydraulic system are improved through rational design of the hydraulic system circuit. The research can provide theoretical direction for the design of large flow hydraulic system and achieve rapid,accurate,stable and intelligent control of the forging manipulator.