An ORing circuit is provided. The ORing circuit includes an input port, an output port, an ORing FET, a comparing circuit, a first transistor and a second transistor. The ORing FET is connected between the input port and the output port and comprises a source connected with the input port, a gate and a drain connected with the output port. The comparing circuit is connected with the input port and the gate. The first transistor comprises a first terminal, a second terminal and a third terminal. The first terminal is connected with the input port and the source, and the third terminal is connected with the gate. The second transistor comprises a fourth terminal, a fifth terminal and a sixth terminal. The fourth terminal is connected with the output port and the drain, and the sixth terminal is connected with the second terminal of the first transistor.