The invention discloses a power supply for a face detection system, which is characterized in that it mainly consists of a control chip U2, a diode rectifier U1, a field effect transistor MOS1, a triode VT1, a diode D1, a polar capacitor C1, a polar capacitor C4, and a diode D4 , a polar capacitor C5, a voltage detection circuit connected to the VDD-pin of the control chip U2, the negative output terminal of the diode rectifier U1, and the emitter of the triode VT1, respectively, and the positive electrode of the polar capacitor C5 and the field effect transistor The drain of MOS1 is composed of a base constant current drive circuit connected to the FB pin of the control chip U2. The present invention can effectively reduce the leakage current and loss current of the input current, and can suppress the abnormal fluctuation of the input current, so that the input current remains stable, thereby improving the stability of the output voltage and current of the present invention, and effectively improving the The detection accuracy of the detection system.