The invention relates to a can printing machine numerical-control system based on a digital motion controller, and the can printing machine numerical-control system comprises a human-machine communication touch screen operation control module based on a windows platform, a digital motion controller, a motion actuation module and a reducer module, wherein the human-machine communication touch screen operation control module based on the windows platform is connected with the digital motion controller through an Ethernet network cable, and the digital motion controller and an input/output (I/O) sub-board of the digital motion controller are directly connected with an I/O signal connection terminal of the motion actuation module, i.e. an alternative-current servo motor; the digital motion controller is connected with the motion actuation module i.e. the alternative-current servo motor through an Ethernet bus; and the digital motion controller is connected with four alternative-current servo motors to form a double-closed-loop motion control system. The system is simple in structure, each constitutional part is relatively independent, partial hardware can be directly purchased in the market to be used as the constitutional part, not only can the performance be comparable and the cost be reduced, but also simplicity in assembling, application and upgrading can be realized, and the tank printing machine numerical-control system can be mass popularized to a pop can printing production line and similar iron production lines.