The invention relates to an embedded technology, and specifically relates to a double Ethernet and double RS-422 mutual transformation communication system and method. The communication system comprises a first user interface unit, a network port transformer unit, an Ethernet controller unit, a main controller unit, an RS-422 isolation transformation unit, a network data transmission cable and a second user interface unit which are sequentially connected. The communication system is flexible and convenient in parameter setting, can switch quickly, stably and seamlessly, not only ensures the reliability and the rapidity of the communication system, but also can adapt to working occasions with complex electromagnetic environments, long transmission distance and high communication accuracy. The communication system has a high anti-interference ability and reliability, can effectively detect and position a fault and timely switch to a standby network, thereby ensuring the timeliness of information transmission in the field. The communication system is used in occasions such as a ship integrated power energy management system, a distributed substation, a power electronic transformationdevice and an industrial field monitoring system which have very high requirements for real-time data.