A switching power converter comprises a switch, a pulse width modulation (PWM) circuit, a rectifying filter circuit and a current limited protection circuit. The input terminal of the rectifying filter circuit is coupled to an input voltage via the switch. The current limited protection circuit comprises an amplifier and a pulse-width modulator. The amplifier detects an induced voltage while a working current flows through the switching power converter, and amplifies the induced voltage so as to generate a comparison voltage. The pulse-width modulator receives an output from the amplifier, determines an output of the pulse-width modulator according the comparison voltage and a reference voltage, and limits the working current according to the output of the pulse-width modulator.