An over-voltage and over-temperature detecting circuit includes a voltage-limiting circuit, a temperature sensing circuit, a current source, a first comparing circuit and a second comparing circuit. The equivalent resistance of the temperature sensing circuit varies with the temperature. The current source provides a first current to a detecting terminal, so that a detecting voltage is generated at the detecting terminal. By comparing the magnitude of the detecting voltage with the first reference voltage value, the first comparing circuit generates a corresponding temperature status signal. By comparing the magnitude of the detecting voltage with the second reference voltage value, the second comparing circuit generates a corresponding voltage status signal. If the temperature exceeds the temperature upper limit, the temperature status signal is in an enabling status. If the first voltage exceeds the voltage upper limit, the voltage status signal is in an enabling status.