Embodiments of the present invention disclose a signal transmission method and apparatus. The apparatus includes an LTE-U processing unit, a Wi-Fi processing unit, an antenna unit, and a coupling apparatus. After receiving an LTE-U signal sent by the LTE-U processing unit, the coupling apparatus divides the LTE-U signal into a first LTE-U signal to be sent to the antenna unit and a second LTE-U signal to be sent to the Wi-Fi processing unit, so that the Wi-Fi processing unit does not send a Wi-Fi signal; and after receiving a Wi-Fi signal sent by the Wi-Fi processing unit, the coupling apparatus divides the Wi-Fi signal into a first Wi-Fi signal to be sent to the antenna unit and a second Wi-Fi signal to be sent to the LTE-U processing unit, so that the LTE-U processing unit does not send an LTE-U signal.