A band-gap reference circuit including: mirror current branch circuits, band-gap paths, and an operational amplifier. Each mirror current branch circuit includes a mirror PMOS transistor and an auxiliary PMOS transistor. A drain of each mirror PMOS transistor is connected with a source of a corresponding auxiliary PMOS transistor, and a drain of said each auxiliary PMOS transistor is connected to a top end of a corresponding band-gap path, each gate of each mirror PMOS transistor is connected with an output port of the operational amplifier. A gate of each auxiliary PMOS transistor is connected to a first bias voltage. A substrate electrode of each mirror and auxiliary transistor is all connected to a source voltage. The output port of the operational amplifier outputs a high level less than the source voltage, the first bias voltage is less than an output voltage signal of the operational amplifier.