The invention discloses a circuit and method for increasing the current overload protecting ability of a power supply. The circuit comprises a DCR current sampling circuit, an RC matching conversion circuit and an operational amplifier circuit. The circuit has the advantages that the current sampling circuit adopts simple and practical inductive current sampling, and transmission output currents or power can be presented in real time; the RC matching conversion circuit adopts a simple RC network, and easy wiring can be achieved without a large space during PCB layout; the optional amplifier circuit does not have a delay time difference and can transmits a real-time current signal at any time; all the circuits do not have the delay time difference, power supply overload protecting ability is increased, the lossless sampling circuit is provided, loss can be reduced, and efficiency can be increased; the circuit is low in PCB space occupation, and the PCB layout is facilitated; the DCR current detecting circuit uses an induction parasitic resistor to measure the load currents and is fast in response.