Embodiments of this application provide a data transmission method and apparatus. The method includes: receiving data sent by a terminal in an inactive state, where the data includes to-be-sent data sent by the terminal and identification information of the terminal; determining an anchor base station of the terminal based on the identification information; and sending the data to the anchor base station, so that the anchor base station sends the data to a core-network device. The uplink data of the terminal is forwarded to the anchor base station by using a serving base station and through an interaction between the anchor base station and the serving base station that currently provides an air interface resource for the terminal, and is then transmitted to a core network.