The invention discloses an Ethernet transmission circuit. The Ethernet transmission circuit comprises a protocol conversion chip LAN8720A, an isolating transformer and an RJ45 interface, wherein the protocol conversion chip LAN8720A is connected with a filter circuit; an input end of the isolating transformer is connected with a pull-up resistor and a 3.3V power supply; an EMC (Electro Magnetic Compatibility) boosting circuit is arranged between the isolating transformer and the RJ45 interface; a protocol conversion chip LAN8720A filter network consisting of C22, C23, C24, C25, C26, C27, C28 and C29 is arranged, a drive capacity enhancement network consisting of R2, R3, R4 and R5 is arranged, a compatibility enhancement network consisting of R7, R8, R9 and R30 is arranged, and the effect of the isolating effect is combined, so the isolation and the compatibility are improved, the networking speed is improved, and the stability for work of an Ethernet unit is greatly enhanced.