Low gravity on moon is simulated on earth surface，and simulator gravity compensation is needed. Macro and micro mechanism can meet the requirements of large travel and high precision. Constant tension control gravity compensation is designed with followed mass center constant tension principle，which can provide multiple suspension points for lunar rover comprehensive experiment. Mechanics analysis and vibration analysis for tension control mechanism is carried on. Describes emphasis for the control system. A large number of field test and different condition test showed that it could satisfy the simulator large travel movement and high precision gravity compensation，and the accuracy is up to 98%，which can meet the experiment requirements. This system has been used in a certain product experiment for institute.