This application discloses a beam training method, a communication device, a chip system, and a storage medium. The method includes: performing, by a transmit device, clear channel assessment on sectors corresponding to an antenna of the transmit device; and sending, by the transmit device in a sector whose result of clear channel assessment is idle, a training signal to a receive device, where the training signal is used to perform beamforming training on the antenna. With this solution, beamforming training efficiency can be improved and resource utilization can be increased.