During the liver intervention surgery, the excellent doctor with the help of CT image need puncture the patient several times to find the correct tumor position. Thus, the pain increases for the patient. For the problem a low-cost auxiliary robot system with the help of virtual reality technology for liver invasion surgery is introduced. The auxiliary arm can indicate the punctuation path for doctor and the virtual reality system can find the difference between the planning path of simulation and actual indication path of robot. Then the error can be compensated by modifying and updating the simulation model. Thus the system based on virtual reality is more accuracy and more effective.