The invention discloses a control circuit of a power saver and a control method thereof. The control circuit of the power saver comprises an input contactor MC1, an air switch NFB1, a pressure regulator, a power saving output contactor MC2, a bypass output contactor MC3 and a manual bypass air switch NFB2, wherein the input contactor MC1, the air switch NFB1, the pressure regulator and the power saving output contactor MC2 are communicated with each other; the bypass output contactor MC3 and the manual bypass air switch NFB2 are connected parallel to the circuit; and a corresponding output circuit is automatically converted by detecting the anomaly of input voltage and output voltage to control the stability and the accuracy of the output voltage, thereby saving energy sources. The control circuit of the power saver has the advantages of energy saving, automatic conversion and stable voltage control.