Embodiments of the present invention provide a traffic flow splitting method and apparatus. In a process of accessing a 3GPP network by UE, an eNB in the 3GPP network sends a first multiflow aggregation instruction to the UE, to instruct the UE to establish a first multiflow aggregation channel between the UE and the eNB via a non-3GPP network. The UE establishes the first multiflow aggregation channel. The first multiflow aggregation channel is used for transmitting a part of data in a downlink traffic flow for the UE, where the part of data is offloaded to the non-3GPP network for transmission, and other data in the downlink traffic flow is offloaded to a 3GPP channel for transmission. In the method, different data packets in a same traffic flow can be simultaneously transmitted in the 3GPP network and the non-3GPP network.