The invention discloses a kind of multi-port and multi-chain communication network backup control method, which is applied to the dual-port primary backup, each port has two transmitting and receiving models, the network loop has a primary port and three backup ports, in the exchanging network which is connected crossly, the primary port and the backup port at the same side are the fellow ports each other, each port has two transmitting and receiving models, which are connected to one port of the opposite port through a single chain, each receiving and transmitting model can carries on transmitting and receiving of group package, each port selects data received by a receiving and transmitting model; in switch, the active inverse the port, the passive side switches the receiving and transmitting model, the two ports can witch the models circularly. After receiving the detecting package of the opposite one, it controls the port enter the fixed mode, the invention can upgrades the reliability of the network and it can switch to the backup network when the network has failure.