This application describes examples of a data processing method and apparatus. In one example, the method includes: If a target buffer that is corresponding to a target priority and that is on a network device reaches a first threshold, the network device sends a pause message to an upstream device, so that the upstream device stops sending a first data packet corresponding to the target priority. If a duration in which the network device stops buffering a second data packet is greater than a preset duration, and the target buffer falls back below a second threshold, the network device sends a sending resumption message to the upstream device, so that the upstream device sends a third data packet corresponding to the target priority.