A monitoring system includes at least one CNC device and a monitoring device. Each of the CNC devices includes a movement control unit, a first document module stores the IP address and the related parameters of the CNC device, a human machine interface (HMI) receives a first input instruction, and a controller reads the related parameters from the first document module according to the first input instruction and outputs a movement control instruction to the movement control unit, and stores the movement parameters in the first document module. The monitoring device includes a second document module stores the IP address of the CNC device and the movement parameters of the CNC device, a display device, a processor reads the movement parameters from the second document module according to a second input instruction, and displays the movement parameters via the display device.