The invention provides a two-stage isolation type Ethernet dual-redundancy communication system. The two-stage isolation type Ethernet dual-redundancy communication system comprises a main controllerunit, a preceding stage isolation conversion unit, an Ethernet controller unit, a final-stage isolation conversion unit, a data network transmission cable and a user interface unit, all of which are connected successively. The two-stage isolation type Ethernet dual-redundancy communication system comprises two independent Ethernet peripheral circuits which can realize a redundancy switching function; that is to say, when one circuit is in fault or is damaged, the system is automatically switched to the other circuit to guarantee data reliability when the system communicates with an external device. The two-stage isolation type Ethernet dual-redundancy communication system is particularly suitable for the occasions with far communication distances, high communication precision requirementsand strong electromagnetic interference in an on-site work environment, such as a ship integrated power energy management system, a distributed transformer substation, a power electronic conversion device and an industrial on-site monitoring system.