A method for transmitting data includes a first primary network device receives measurement result information of a secondary network device sent by a terminal device during access to the first primary network device, the measurement result information being used for indicating the quality of a link between the secondary network device and the terminal device; the first primary network device determines, according to the quality of the link between the secondary network device and the terminal device, to establish a secondary connection between the secondary network device and the terminal device; the first primary network device establishes the secondary connection. Thus the transmission load of the first primary network device can be reduced.