This application provides a BIER multicast traffic statistics collection method, a device, and a system. The method includes: A first network device obtains a first BIER packet. The first network device performs traffic statistics collection on the first BIER packet based on multicast flow information, to obtain a traffic statistics collection result of the first BIER packet, where the multicast flow information is used to identify a multicast flow to which the first BIER packet belongs. The first network device sends the multicast flow information and the traffic statistics collection result of the first BIER packet to a controller.