Embodiments of this application provide a communication method, a device, and a system, to resolve an out-of-order problem caused by per-packet traffic splitting. The method includes: determining, by a sending device, a sequence identifier of a to-be-transmitted data packet and an identifier of a first link for transmitting the data packet; and sending, by the sending device, the data packet to a receiving device, where a header of the data packet includes the identifier of the first link and the sequence identifier, the identifier of the first link is used to identify the first link, and the sequence identifier is used to identify a sending order of the data packet over the first link or in a link group to which the first link belongs.