In this paper, the research of the dynamics for the constant force polishing robot system as the goal, through the establishment of the dynamics equations for the end of the robot polishing, a modal analysis of the end of the robot is analyzed. It is obtained its static characteristic and vibration characteristics by the analysis results and verified the meeting requirements of the stiffness and the strength. By comparing the before and the after installation of terminal buffer actuator force was verified by the experiment, the feasibility and stability constant of the system for the constant force polishing on the double-robot are obtained.