This application provides a subflow establishment method. A local-end device obtains an identifier of an operator currently accessed by a network interface card of the local end device. The local-end device obtains a plurality of IP addresses of a peer-end device and identifiers of operators to which the plurality of IP addresses are homed; and establishes, by matching a plurality of operators corresponding to the local-end device and the plurality of operators corresponding to the peer-end device, a subflow between an IP address pair homed to a same operator. In this way, the established subflow does not cross operators as far as possible. This reduces negative impact of cross-operator communication of some subflows on transmission performance of a multipath connection, thereby better leveraging an advantage of the multipath connection in transmission performance in comparison with a single-path connection.