The application provide a packet sending method, a router, and a service switching entity. According to the application, a router determines a flow group identifier of a service packet and information about a next-hop service switching entity according to a user identifier and IP 5-tuple information; and forwards the packet to the next-hop service switching entity according to the information about the next-hop service switching entity, so that the next-hop service switching entity determines a corresponding destination service instance according to the user identifier, the flow group identifier, a router identifier, and a processing result, and forwards the packet to the destination service instance, to perform corresponding service processing, thereby implementing service packet forwarding among service instances. The router in the method provided in the embodiments has a flow steering function, and steers a flow to a specified path to perform node-by-node processing.