The invention relates to a band-gap reference circuit. The band-gap reference circuit comprises a reference voltage source VREF, a band-gap core circuit, a negative feedback circuit and a starting circuit, wherein gate voltage V_REG is stretched by the reference voltage source VREF so that internal voltage pre-stabilization can be achieved, an internal voltage pre-stabilizing circuit is formed, the band-gap core circuit is provided with an automatic biasing cascode amplifying circuit used for increasing a power supply rejection ratio, the negative feedback circuit provides the supply voltage VDD, processed through voltage stabilization, for the band-gap core circuit, and the starting circuit stretches the reference voltage source VREF when work begins so that the automatic biasing cascode amplifying circuit can work normally. According to the band-gap reference circuit, due to the facts that the supply voltage VDD processed through voltage stabilization is provided for the band-gap core circuit through the negative feedback circuit, and the automatic biasing cascode amplifying circuit is adopted inside for increasing the power supply rejection ratio, area and power consumption are saved.