This application discloses a packet transmission method and apparatus, and a device. After receiving a first packet, a first service chain forwarding device performs policy routing matching. When a first policy is found for the first packet, the first service chain forwarding device obtains a first redirection address corresponding to the first policy, and determines a first route set based on the first redirection address. The first route set includes a first primary route and a first backup route. A next hop of the first primary route is a first device, and a next hop of the first backup route is a second device. The first service chain forwarding device forwards the first packet to the first device when the first primary route works normally. The first service chain forwarding device sends the first packet to the second device when the first primary route is faulty. In this application, the primary and backup routes corresponding to the first redirection address are generated in advance. When the first primary route is faulty, the first packet is directly sent to the second device through the first backup route, and bypass is performed without relying on refreshing the route by a control plane. This can improve a fault convergence speed of a service chain.