An output protection circuit used for a power converter having an operational amplifier, a diode, a number of voltage-dividing resistors, and a switch tube. In this circuit, the voltage-dividing resistors are connected in series to form a voltage-dividing network, of which one node is connected to a reference level end Vref of a PWM control module of the converter, while the other node is grounded. A voltage dividing point M is coupled to an inverting input end of the operational amplifier AR1.