In a load sharing method and a router device, each of the router devices in a load sharing relationship obtains load sharing information of all downstream router devices that are in a load sharing relationship with the router device, and when determining load sharing information of the router device, the router device determines the load sharing information of the router device according to the load sharing information of all the downstream router devices that are in a load sharing relationship with the router device, so that a disturbance factor of the router device is different from disturbance factors of all the downstream router devices that are in a load sharing relationship with the router device. Therefore, a coupling degree of load sharing information of all the router devices in a load sharing relationship in the network is reduced, and load sharing at all levels is even.