The present invention discloses a surge protection circuit for a line driver. The surge protection circuit includes a transistor, including a first terminal coupled to a positive output pad of the line driver and a second terminal coupled to a negative output pad of the line driver, an inverter, including an output terminal coupled to a third terminal of the transistor, and a first RC circuit, including a resistor having a terminal coupled to an input terminal of the inverter and another terminal coupled to a power supply, and a capacitor having a terminal coupled to the input terminal of the inverter and another terminal coupled to a ground. A first RC time constant of the first RC circuit is substantially equal to or greater than a period of a differential mode surge signal.