The failure rate of implanting screws only by surgeon hands is high in minimally invasive spine surgery. It can be reduced significantly by adopting robots, however, the robot is restricted when completing the operation automatically because of the complexity and uncertainty of the surgical environment, as well as the safety requirements of the operation. By establishing the surgical space velocity field and designing velocity field controller, the kinematics and dynamics models of robot are developed to realize the simulation and experiment of implanting pedicle screws by the robot automatically. Compared with traditional time trajectory control, the advantages of velocity field control method in the process of implanting pedicle screw automatically are verified by the simulation test, in which the accuracy of operation trajectory is guaranteed and the damage to the nerve root is avoided under disturbance conditions. The experiment proves the feasibility of the velocity field control method.