The invention relate to a device and a method for controlling a single-bus modular digital actuator of a robot. The device comprises an actuator control unit, a direct-current motor, a communication module, a speed reduction mechanism, position and temperature sensors and a current protection circuit. The method includes that the actuator control unit computes control parameters according to the running temperatures, driving currents of the motor and the position of the actuator and outputs the control parameters to a motor control circuit; the communication module receives control instructions of an upper computer and feeds information of the current position of the actuator, the current speed of the actuator and the like to the upper computer; a high rotational speed and low torque of the motor are converted into a low rotational speed and high torque by the speed reduction mechanism and an output mechanism, and the low rotational speed and the high torque are outputted by the speed reduction mechanism and the output mechanism; the position sensor, the temperature sensor and the current protection circuit are respectively used for feeding current position signals of the actuator, the running temperatures and the driving currents of the motor to the actuator control unit, so that closed-loop high-precision safety control can be implemented. The device and the method have the advantages of overcurrent, overvoltage and over-temperature protection, capability of preventing overload or over-temperature damage, high response speed, zero dead zones and high control precision.