In the field of AC servo motion control, serveral control difficulties were caused by the large difference of the two axis load inertia, and the demand of the rated running speed and the high positioning accuracy. To solve these problems, a simple and effective synchronous control method was proposed, and it was verified in the experiment. The method included two parts: the design of the synchronous control and the error compensation algorithm. Firstly, a masterslave control method based on virtual spindle was designed to realize synchronous instruction output with inertia matching. Considering the load characteristics, an error compensation method based on weighted coupling was proposed, which could realize fast and stable synchronous error compensation. Simulation and experimental results show that the method can meet the requirements of positioning and synchronous control accuracy of the servo motion system, meanwhile, the stability and compensation response speed of the system are improved to a certain extent, and the method works well in engineering applications.