The invention relates to a protective circuit used for a brushless direct current electrode. A first input end is connected with an output end by a first resistor, a first diode and a fourth resistor which are connected in series, wherein, an anode of the first diode is connected with the first resistor, a cathode of the first diode is connected with the fourth resistor, and a first sense resistor is connected with the first input end and the ground; a second input end is connected with an output end by a second resistor, a second diode and the fourth resistor which are connected in series, wherein, an anode of the second diode is connected with the second resistor, and a cathode of the second diode is connected with the fourth resistor, a second sense resistor is connected with the second input end and the ground; a third input end is connected with an output end by a third resistor, a third diode and the fourth resistor which are connected in series, wherein, an anode of the third diode is connected with the third resistor, a cathode of the third diode is connected with the fourth resistor, and a third sense resistor is connected with the third input end and the ground; and a fifth resistor is connected with an output end and the ground. The protective circuit of the invention has simple structure, is convenient for cost control; only an I/O interface of a data processing chip is used, thereby facilitating the selection to the data processing chip.