A surge preventing circuit of a local area network (LAN) connector is suitable for being coupled to a plurality of transformers disposed in the local area network connector. The surge preventing circuit includes a conjugate coil module and a surge absorbing element. The conjugate coil module has at least one conjugate coil. The conjugate coil has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal and the second input terminal of the conjugate coil are coupled to the center tapped terminal of the respective transformer, respectively. A first terminal of the surge absorbing element is connected to ground, and a second terminal is coupled to the first output terminals and the second output terminals.