Embodiments of the present invention provide a communication method, a user equipment, and a single radio controller. The method includes: establishing, by a user equipment, a first connection with an SRC by using a first communications network; and sending, by the user equipment, NAS signaling or Layer 3 signaling of a second communications network to the SRC by using the first connection, and/or receiving NAS signaling or Layer 3 signaling of a second communications network from the SRC by using the first connection. Therefore, in the embodiments of the present invention, NAS/L3 signaling of a second communications network is transmitted over the first connection that is established in a first communications network, so that a service can flexibly switch between different RATs, and the system efficiency is improved.