In a detection packet transmission method, a first network device receives a first packet, where the first packet includes a detection header indicating a network device to detect, based on the detection header, transmission performance of a service flow in which the first packet is located, and the first network device is an edge network device in a first network domain. The first network device obtains a second packet based on the first packet, where the second packet includes processing identification information and the detection header, the processing identification information indicates a second network device to process the detection header, and the second network device is a next-hop device of the first network device on a transmission path of the service flow. The first network device sends the second packet to the second network device.