Abstract: An output voltage detecting circuit includes a conducting structure, a voltage regulator, a first resistor and a second resistor. The conducting structure includes a power output return terminal, a first contact and a second contact. A compensating voltage is generated between the first and second contacts when an output current flows through the first and second contacts. The voltage regulator adjusts a first current according to a voltage across a first circuit terminal and the ground terminal of the voltage regulator, thereby generating a detecting signal according to the first current. An output voltage across the positive power output terminal and the power output return terminal is subject to voltage division by the first and second resistors to generate a divided voltage. The voltage across the first circuit terminal and the ground terminal of the voltage regulator is equal to a difference between the divided voltage and the compensating voltage.