The invention provides a link redundancy communication system based on EtherCAT. The system includes a master station processor which is used for controlling input and output of an Ethernet signal, a master station standby processor which is connected with the master station processor of the communication system through a synchronous bus and used for performing redundancy backup on the master station processor and controlling input and output of an Ethernet signal, a coupled communication board which is connected with the master station processor and the master station standby processor through two links and used for inputting an Ethernet signal from the master station processor or the master station standby processor to the coupled communication board, and a terminal board which is connected with the coupled communication board at one end in order to input a signal from the coupled communication board to the terminal board and is connected with the master station processor and the master station standby processor through two links at the other end in order to output an Ethernet signal from the terminal board to the master station processor or the master station standby processor, thus forming a multi-link loop network redundant path. The communication system of the invention is of higher reliability, stability and safety.