A transmission quality detection method, applied to an ingress device in a transmission quality detection system, wherein the transmission quality detection system comprises a controller and a plurality of network devices, the plurality of network devices comprise the ingress device and an egress device, and the method comprises: determining, from a received service packet, a service packet belonging to a target service flow group, wherein the target service flow group service flow group includes a plurality of service flows identified by 5-tuple information, wherein the 5-tuple information includes a source IP address, a destination IP address, a source port, a destination port, and a protocol number; obtaining transmission quality information of the target service flow group based on a detection packet belonging to the target service flow group, wherein the detection packet comprises at least one service packet belonging to the target service flow group; and reporting a flow identifier of the target service flow group and the transmission quality information of the target service flow group to the controller, to enable the controller to determine transmission quality of the target service flow group based on the flow identifier of the target service flow group and the transmission quality information of the target service flow group that are reported by the ingress device, wherein the service packet belonging to the target service flow group meets any one or a combination of a plurality of the following conditions: the service packet is transmitted through a target transmission network, the service packet is transmitted on a target transmission path, the service packet is received through a target port of the ingress device, the service packet is transmitted through the egress device, and the service packet has a target priority. determining, from a received service packet, a service packet belonging to a target service flow group, wherein the target service flow group service flow group includes a plurality of service flows identified by 5-tuple information, wherein the 5-tuple information includes a source IP address, a destination IP address, a source port, a destination port, and a protocol number; obtaining transmission quality information of the target service flow group based on a detection packet belonging to the target service flow group, wherein the detection packet comprises at least one service packet belonging to the target service flow group; and reporting a flow identifier of the target service flow group and the transmission quality information of the target service flow group to the controller, to enable the controller to determine transmission quality of the target service flow group based on the flow identifier of the target service flow group and the transmission quality information of the target service flow group that are reported by the ingress device, wherein the service packet belonging to the target service flow group meets any one or a combination of a plurality of the following conditions: the service packet is transmitted through a target transmission network, the service packet is transmitted on a target transmission path, the service packet is received through a target port of the ingress device, the service packet is transmitted through the egress device, and the service packet has a target priority.