A downlink traffic flow splitting method, comprising: receiving, by user equipment, UE, a first multiflow aggregation instruction sent by an evolved NodeB, eNB, in a 3rd Generation Partnership Project, 3GPP, network, wherein the first multiflow aggregation instruction is used to instruct the UE to establish a first multiflow aggregation channel between the UE and the eNB via a non-3GPP network, the first multiflow aggregation channel is used for transmitting a part of data in a downlink traffic flow for the UE, wherein 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 that is in the 3GPP network and that is between the UE and the eNB for transmission, the first multiflow aggregation instruction is carried in a radio resource control connection configuration message, the non-3GPP network is a wireless local area network, WLAN; and establishing, by the UE, the first multiflow aggregation channel; wherein the method further comprises: receiving, by the UE, a first downlink data flow sent by the eNB by using the 3GPP channel; receiving, by the UE, a second downlink data flow sent by the eNB by using the first multiflow aggregation channel; and aggregating, by the UE, the first downlink data flow with the second downlink data flow to form one downlink traffic flow, wherein the downlink traffic flow for the UE is split by the eNB into the first downlink data flow and the second downlink data flow; wherein the second downlink data flow that is sent by the eNB by using the first multiflow aggregation channel and is received by the UE comprises a bearer identifier corresponding to the downlink traffic flow; wherein before the aggregating, by the UE, the first downlink data flow with the second downlink data flow to form one downlink traffic flow, the method further comprises: determining, by the UE according to information comprised in the second downlink data flow, a bearer corresponding to the second downlink data flow, wherein the information comprised in the second downlink data flow is the bearer identifier corresponding to the downlink traffic flow; and determining, by the UE, that a bearer corresponding to the first downlink data flow and the bearer corresponding to the second downlink data flow are a same bearer. receiving, by user equipment, UE, a first multiflow aggregation instruction sent by an evolved NodeB, eNB, in a 3rd Generation Partnership Project, 3GPP, network, wherein the first multiflow aggregation instruction is used to instruct the UE to establish a first multiflow aggregation channel between the UE and the eNB via a non-3GPP network, the first multiflow aggregation channel is used for transmitting a part of data in a downlink traffic flow for the UE, wherein 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 that is in the 3GPP network and that is between the UE and the eNB for transmission, the first multiflow aggregation instruction is carried in a radio resource control connection configuration message, the non-3GPP network is a wireless local area network, WLAN; and establishing, by the UE, the first multiflow aggregation channel; wherein the method further comprises: receiving, by the UE, a first downlink data flow sent by the eNB by using the 3GPP channel; receiving, by the UE, a second downlink data flow sent by the eNB by using the first multiflow aggregation channel; and aggregating, by the UE, the first downlink data flow with the second downlink data flow to form one downlink traffic flow, wherein the downlink traffic flow for the UE is split by the eNB into the first downlink data flow and the second downlink data flow; receiving, by the UE, a first downlink data flow sent by the eNB by using the 3GPP channel; receiving, by the UE, a second downlink data flow sent by the eNB by using the first multiflow aggregation channel; and aggregating, by the UE, the first downlink data flow with the second downlink data flow to form one downlink traffic flow, wherein the downlink traffic flow for the UE is split by the eNB into the first downlink data flow and the second downlink data flow; wherein the second downlink data flow that is sent by the eNB by using the first multiflow aggregation channel and is received by the UE comprises a bearer identifier corresponding to the downlink traffic flow; wherein before the aggregating, by the UE, the first downlink data flow with the second downlink data flow to form one downlink traffic flow, the method further comprises: determining, by the UE according to information comprised in the second downlink data flow, a bearer corresponding to the second downlink data flow, wherein the information comprised in the second downlink data flow is the bearer identifier corresponding to the downlink traffic flow; and determining, by the UE, that a bearer corresponding to the first downlink data flow and the bearer corresponding to the second downlink data flow are a same bearer. determining, by the UE according to information comprised in the second downlink data flow, a bearer corresponding to the second downlink data flow, wherein the information comprised in the second downlink data flow is the bearer identifier corresponding to the downlink traffic flow; and determining, by the UE, that a bearer corresponding to the first downlink data flow and the bearer corresponding to the second downlink data flow are a same bearer.