The invention discloses a band-gap reference circuit implemented based on two threshold voltage metal oxide semiconductor (MOS) devices, belongs to an analogue integrated circuit technology, and particularly relates to a band-gap reference circuit structure capable of decreasing cost, reducing power consumption and improving performance. The circuit structure comprises a negative temperature coefficient current generation circuit, a positive temperature coefficient current generation circuit, a starting circuit, a biasing circuit and an output circuit. The negative temperature coefficient current generation circuit is implemented by adopting the two threshold voltage MOS devices, and generated negative temperature coefficient current has a second-order temperature characteristic, so that the temperature performance of output reference voltage can be effectively improved, a layout area can be reduced at the same time, the power consumption of the circuit can be reduced and manufacture cost can be decreased.