A green bridge circuit for adjusting a DC power source and an AC power source is provided. The green bridge circuit includes a bridge circuit and a bias adjustment circuit. The bridge circuit includes four transistors connected to a first power terminal, a system load, and a second power terminal. The bias adjustment circuit has an input terminal coupled to an output terminal of the bridge circuit and an output terminal coupled to control terminals of the transistors. The bias adjustment circuit changes bias voltages of the control terminals of the transistors according to a rectified voltage outputted by the bridge circuit. In this way, loss is reduced, heat generation is prevented, and transmission loss is addressed.