The present invention discloses a data sending method and a communications device. The method includes: sensing, by a communications device, a carrier located in a first unlicensed frequency band, where the first unlicensed frequency band includes at least one carrier; and sending, by the communications device, data on a carrier whose channel state is sensed to be idle. The communications device senses a first carrier in the first unlicensed frequency band, and sends the data on the first carrier that is successfully sensed to be idle. Another communications device may also sense in the first unlicensed frequency band, and send data in the first unlicensed frequency band when sensing successfully. Therefore, users of different services may fairly contend and coexist in an unlicensed frequency band.