Abstract: The concept of virtual instruments was applied in a multi-motor control system to monitor each motor’s movement track and character of current, in order to realize optimal control. The multi-motor control system adopted client/server structure based on controller area network (CAN) bus, and the virtual instrument became the host unit replacing the motor control center in the development phase to debug and measure each motor control client unit. The visual instrument was built using CAN card and visual basic. It could adjust proportional-integral differential(PID) parameters of motors controller online, show the result digitally and graphically, update the digital signal processor (DSP) and field programmable gate array (FPGA) program on board and emulate some testing environment, and dramatically improve the development efficiency and product quality of certain type of X-ray machine.