This paper mainly studies the active compensation control of electromechanical compound constant force system based on data model. For the needs of high-precision and low-gravity assembly and testing of space structures on the ground in the vertical direction, in order to improve the output accuracy of the existing electromechanical composite constant force system, an error model is established through data obtained from experiments, and the error model is introduced to actively compensate, then actual control experiments are carried out to verify the effectiveness of the active compensation control of the electromechanical composite constant force system based on the data model.