An internet interface protecting circuit, comprising an ethernet interface, a first isolating transformer, a second isolating transformer, a network signal processing chip, and a first interference defending circuit, a second interference defending circuit; wherein, the ethernet interface, is used for receiving and sending a network signal; the first isolating transformer, is used for separating a receiving data end of the ethernet interface from the network signal receiving chip; the second isolating transformer, is used for separating a sending data end of the ethernet interface from the network signal receiving chip; the first interference defending circuit, is used for defending common-mode interference and differential-mode interference of the receiving data end of the ethernet interface; the network signal processing chip, is used for processing the network signal; the receiving data end of the ethernet interface is connected with a primary side of the first isolating transformer; the first interference defending circuit is connected between a secondary side of the first isolating transformer and the network signal receiving chip; the sending data end of the ethernet interface is connected with a primary side of the second isolating transformer; a secondary side of the second isolating transformer is connected with the network signal processing chip; the second interference defending circuit, is used for defending common-mode interference and differential-mode interference of the sending data end of the ethernet interface; the second interference defending circuit is connected between the secondary side of the second isolating transformer and the network signal receiving chip; wherein the first interference defending circuit comprises a first catching diode, a second catching diode, a first resistor and a second resistor; wherein, an anode of the first catching diode and an anode of the second catching diode are both earthed; a cathode of the first catching diode is connected with a first end of a secondary side coil of the first isolating transformer; a cathode of the second catching diode is connected with a second end of the secondary side coil of the first isolating transformer; the cathode of the first catching diode is also connected with a receiving data negative end (RX2-) of the network signal processing chip through the first resistor; the cathode of the second catching diode is also connected with a receiving data positive end (RX2+) of the network signal processing chip through the second resistor. the ethernet interface, is used for receiving and sending a network signal; the first isolating transformer, is used for separating a receiving data end of the ethernet interface from the network signal receiving chip; the second isolating transformer, is used for separating a sending data end of the ethernet interface from the network signal receiving chip; the first interference defending circuit, is used for defending common-mode interference and differential-mode interference of the receiving data end of the ethernet interface; the network signal processing chip, is used for processing the network signal; the receiving data end of the ethernet interface is connected with a primary side of the first isolating transformer; the first interference defending circuit is connected between a secondary side of the first isolating transformer and the network signal receiving chip; the sending data end of the ethernet interface is connected with a primary side of the second isolating transformer; a secondary side of the second isolating transformer is connected with the network signal processing chip; the second interference defending circuit, is used for defending common-mode interference and differential-mode interference of the sending data end of the ethernet interface; the second interference defending circuit is connected between the secondary side of the second isolating transformer and the network signal receiving chip; wherein the first interference defending circuit comprises a first catching diode, a second catching diode, a first resistor and a second resistor; wherein, an anode of the first catching diode and an anode of the second catching diode are both earthed; a cathode of the first catching diode is connected with a first end of a secondary side coil of the first isolating transformer; a cathode of the second catching diode is connected with a second end of the secondary side coil of the first isolating transformer; the cathode of the first catching diode is also connected with a receiving data negative end (RX2-) of the network signal processing chip through the first resistor; the cathode of the second catching diode is also connected with a receiving data positive end (RX2+) of the network signal processing chip through the second resistor.