Taking the electronic gearbox as the research object, starting from analyzing the motion process of gear machine, the coupling relationship linkage model of the electronic gear box in the motion process was constructed. The singleaxis tracking error and coupling error of the electronic gearbox were studied. Combining with the difficulties of gear processing,a simplified calculation model for coupling errors was presented, a dynamic closedloop compensation technology for phase error of electronic gearbox was developed to control the coupling error of gear processing. Finally, through the application based on GSK218 CNC system, the practicability of the presented scheme was verified.