Embodiments of a session processing method and a device relating to a data network are provided. The method includes a data-network network element in the data network receiving a data network access request sent by a session management function (SMF) network element of the data network, where the data network access request includes an identifier of user equipment UE and a session address to be used by the UE. The data-network network element sends a response message to the SMF, where the response message instructs the SMF to allow the UE to access the data network, so that the SMF establishes a data packet unit session of the UE. The data-network network element detects, based on the session address or the identifier of the UE, that the data packet unit session of the UE needs to be processed, generates a session processing request, and instructs, by using the session processing request, the SMF to process the data packet unit session of the UE.