Embodiments of this application provide a network optimization method, a network optimization system, and a network device, and relate to the communications field. A first network device adjusts, if it is detected that a communications link between the first network device and a second network device is in an abnormal state, a metric of at least one data flow received by the first network device; and the first network device selects a transmission path for the at least one data flow based on adjusted metric, and transmits the at least one data flow to the selected transmission path. In this way, load of the communications link is reduced, and the communications link is restored to a normal state.