A packet processing method implements a QoS guarantee. The method includes: obtaining a flow identification based on packet attribute information and a flow matching rule, generating a flow policy that includes a correspondence between the flow identification and a flow behavior, determining a forwarding path of a packet including the packet attribute information, sending the flow matching rule to an ingress device of the forwarding path, and sending the flow policy to a first network device on the forwarding path. The ingress device adds the flow identification to the packet including the packet attribute information, and sends the packet. The first network device receives the packet including the flow identification, obtains the flow behavior from the flow policy based on the flow identification, and processes the packet in a packet processing mode corresponding to the flow behavior.