The invention belongs to the technical field of the PLC, and discloses a network bridge device, and application, and a communication control method of multiple PLC master stations and multiple PLC slave stations. The device is provided with a plurality of interfaces communicated with the PLC master stations, a plurality of interfaces communicated with the PLC slave stations, and comprises a PLC master station input optimization module, a PLC master station state monitoring module, a PLC slave station input optimization module, and a PLC slave station state monitoring module; the PLC master station input optimization module optimizes one from multiple master station inputs to output to the slave station; the PLC master station state monitoring module monitors each master station according to input data of multiple master stations and stops the master station data forwarding when monitoring that one main station is abnormal; the PLC slave station input optimization module optimizes one from multiple slave station inputs to output to the master station in normal work; the PLC salve station state monitoring module monitors the working state of each slave station according to multiple slave station inputs; the network bridge device organizes network with multiple PLC master stations and the PLC slave stations so as to form a redundancy PLC system, thereby realizing the PLC master and slave station redundancy, the PLC master and slave station working state monitoring, and the PLC master station state synchronization in the redundancy PLC system.