A servo actuator ID setting method is performed by a servo actuator controlling system. The servo actuator controlling system includes a master controller and a plurality of servo actuators. One servo actuator is set to disconnect to a next servo actuator. A plurality of interfaces of the master controller is selected to turn on in sequence. The following steps are repeatedly performed to set servo actuator ID: broadcasting a signal to replace an original ID of each of the plurality of servo actuators with a target ID; the plurality of servo actuators in each branch connecting to the master controller; and replacing the original ID of each of the plurality servo actuator with the target ID.