A service traffic steering method, applied to an uplink classifier, the method comprising: identifying a steering path identifier of a downlink service traffic according to a service traffic steering policy comprising: when the steering path identifier of the downlink service traffic can be directly identified according to an uplink service traffic, directly inspecting the uplink service traffic to obtain the steering path identifier of the downlink service traffic according to the service traffic steering policy; or when the steering path identifier of the downlink service traffic cannot be directly identified according to the uplink service traffic, receiving the downlink service traffic also; and inspecting the uplink and downlink service traffic information jointly to recognize the steering path identifier of the downlink service traffic according to the service traffic steering policy; determining that an internet protocol, IP, 5-tuple or partial information of the IP 5-tuple of the downlink service traffic can be identified and that the IP 5-tuple or the partial information of the IP 5-tuple of the downlink service traffic clearly corresponds to the downlink service traffic; and sending, after it has been determined that the IP 5-tuple or the partial information of the IP 5-tuple can be identified and clearly corresponds to the downlink service traffic, the steering path identifier of the downlink service traffic and description information comprising the determined IP 5-tuple or partial information of the IP 5-tuple of the downlink service traffic to a downlink classifier to enable the downlink classifier to identify and to mark related downlink service traffic with the steering path identifier of the downlink service traffic, wherein the uplink classifier and the downlink classifier are deployed in different network devices. identifying a steering path identifier of a downlink service traffic according to a service traffic steering policy comprising: when the steering path identifier of the downlink service traffic can be directly identified according to an uplink service traffic, directly inspecting the uplink service traffic to obtain the steering path identifier of the downlink service traffic according to the service traffic steering policy; or when the steering path identifier of the downlink service traffic cannot be directly identified according to the uplink service traffic, receiving the downlink service traffic also; and inspecting the uplink and downlink service traffic information jointly to recognize the steering path identifier of the downlink service traffic according to the service traffic steering policy; when the steering path identifier of the downlink service traffic can be directly identified according to an uplink service traffic, directly inspecting the uplink service traffic to obtain the steering path identifier of the downlink service traffic according to the service traffic steering policy; or when the steering path identifier of the downlink service traffic cannot be directly identified according to the uplink service traffic, receiving the downlink service traffic also; and inspecting the uplink and downlink service traffic information jointly to recognize the steering path identifier of the downlink service traffic according to the service traffic steering policy; determining that an internet protocol, IP, 5-tuple or partial information of the IP 5-tuple of the downlink service traffic can be identified and that the IP 5-tuple or the partial information of the IP 5-tuple of the downlink service traffic clearly corresponds to the downlink service traffic; and sending, after it has been determined that the IP 5-tuple or the partial information of the IP 5-tuple can be identified and clearly corresponds to the downlink service traffic, the steering path identifier of the downlink service traffic and description information comprising the determined IP 5-tuple or partial information of the IP 5-tuple of the downlink service traffic to a downlink classifier to enable the downlink classifier to identify and to mark related downlink service traffic with the steering path identifier of the downlink service traffic, wherein the uplink classifier and the downlink classifier are deployed in different network devices.