The application provides a node identifier setting method and device. The main device and each node device are connected to a first serial bus; wherein the output end of the main device is connected to the input end of the first node device through the first serial bus, and the output end of the previous node device is connected to the input end of the later node device through the first serial bus; and the node identifier setting method is applied to the node devices. The node identifier setting method comprises the following steps: receiving node identifier data through the first serial bus;obtaining a node identifier that the main device allocates to the node device from the node identifier data; and setting the obtained node identifier as the node identifier of the node device. By means of the node identifier setting method, the workload of the user is relieved without the need for the user to manually operate the dialing switch; and the additional hardware circuits are not required to add to the node device, therefore, the hardware costs are saved, and the area of the PCB is saved.