A data transmission channel processing method, an apparatus and a system, the method comprising determining, by a session management network element, that a data flow of a packet data unit (PDU) session of a terminal needs to be offloaded, where the PDU session is established by using a 3rd generation partnership project (3GPP) access technology and a non-3GPP access technology, and determining, by the session management network element, to insert an offloading device into a data path of the PDU session, where the data path of the PDU session includes a data transmission channel in the 3GPP access technology or a data transmission channel in the non-3GPP access technology.