A power converter with a negative current detection mechanism is provided. A negative current detecting circuit includes a first operational amplifier, a first transistor and a second transistor. A non-inverting input terminal of the first operational amplifier is connected to a second terminal of a sense resistor. An inverting input terminal of the first operational amplifier is connected to a first terminal of a first capacitor. Control terminals of the first and second transistors are connected to an output terminal of the first operational amplifier. A first terminal of the first transistor is connected to the second terminal of the sense resistor. A second terminal of the first transistor is grounded. A first terminal of the second transistor is connected to the inverting input terminal of the first operational amplifier and the first terminal of the first transistor. A second terminal of the second transistor is grounded.