This application provides an information transmission method and a communications device. A first communications device sends first indication information to a second communications device, where the first indication information indicates a frequency resource used by the second communications device to send data in a time unit and a frequency resource used by the second communications device to receive data in the time unit, the frequency resource used to send data and the frequency resource used to receive data belong to a same frequency band, the frequency resource used to send data and the frequency resource used to receive data are differentiated based on frequencies in the time unit, and the frequency band is a segment of continuous frequency resources in frequency domain. In the foregoing information transmission method, the first communications device can flexibly allocate the frequency resources based on a network requirement, thereby improving resource utilization.