The performance characteristics of the hydraulic supporting system of the inside piercing device directly determine the work status of doubleaction extrusion press, implementation of extrusion process and the quality of products. The simulation model of hydraulic supporting systems of the inside piercing device was built by the use of simulation software SimulationX, and the simulation parameters were set according to the actual working condition of the hydraulic system. The three main working processes such as fast idle forward of main plunger piston, idle forward of piercer and extrusion process with the fixed piercing mandrel were simulated. The velocity, displacement and flow characteristics curve in the three main working processes were analyzed during the working process of the system. The simulation results indicate that the overall performance of the hydraulic supporting system of the inside piercing device is stable, runs well and meets the system performance requirements.