A method of inter-board communication in a router cluster, a router, and a router cluster are provided. The method comprises: the main router configuring and enabling an IP address of the interconnection interface of the main router, and acquiring IP address(es) of other router(s) in the router cluster; other router(s) except the main router configuring and enabling IP address(es) of interconnection interface(s) of other router(s) except the main router respectively, and acquiring the IP address of the main router; the main router establishing communication connections with other router(s) in the router cluster, and enabling the function of communication agent; the main router and the other router(s) in the router cluster transmitting internal control messages of the router cluster through their respective communication agent modules.