An interface control circuit comprises an interface signal transceiver circuit coupled with an interface which includes at least one interface pin for transmitting and/or receiving an interface signal through the interface, and a protection circuit for generating a protection control signal according to a capacitance of a first interface pin. During a predetermined detection time period starting from an attaching event, the protection circuit senses the capacitance of the first interface pin, and determines that there is an electrolytic substance existing and coupled with the first interface pin when the capacitance is larger than a predetermined first capacitance threshold. The protection control signal triggers the interface signal transceiver circuit to execute a protection operation. The interface includes the first interface pin and the second interface pin, and the first interface pin and the second interface pin can be one same pin or separate different pins.