The invention is applicable to the field of detection, and provides a default phase detection device and method of a DC brushless motor control circuit. The method comprises the steps of inputting a preset Hall signal to the DC brushless motor control circuit; receiving a three-phase voltage which is output from the DC brushless motor control circuit and is corresponding to the preset Hall signal; judging whether the three-phase voltage which is output from the DC brushless motor control circuit and is corresponding to the preset Hall signal is matched with the preset Hall signal or not according to an acquisition voltage and a corresponding relation between the acquisition voltage and the Hall signal; and outputting a default phase detection result of the DC brushless motor control circuit to a user according to a matching result and a preset output mode. By the method, automatic default detection of the DC brushless motor control circuit is achieved, a manual fault is avoided, and the manual cost is greatly reduced; and moreover, the device is simple in structure and relatively low in cost, a motor or other equipment is not needed to be matched, the detection speed is fast, the efficiency is high, and 100% detection coverage rate is easily ensured.