This application describes a data transmission method, a terminal device, and a network device. The method may include determining, by a medium access control (MAC) layer of a terminal device, a first MAC control element and a second MAC control element. The method may also include simultaneously transmitting, by the terminal device, the first MAC control element and the second MAC control element on different uplink transmission resources. The data transmission method, the terminal device, and the network device in embodiments of this application help to improve data transmission reliability.