This application describes a link bit error-based processing method and apparatus. A network device may report, to a controller, a bit error rate at which an egress port on the network device is configured to send data traffic. In this way, the controller may collect and accumulate bit error rates at which data traffic is sent through all egress ports on a transmission path, to obtain an accumulated bit error rate of the transmission path. In this way, the controller may determine, based on the accumulated bit error rate of the transmission path, whether to switch a service flow on the transmission path to another transmission path. Therefore, the controller may switch a service flow transmitted on a transmission path with an excessively high accumulated bit error rate to another transmission path with a relatively low accumulated bit error rate for transmission.