Channel access method and device

The invention discloses a channel access method and device, and the method and device are used for improving the channel access capability of LTE-U. The method comprises the steps that a communication device resets the size of a competitive window to be used in the channel access process and the number of observation time slots in the current channel access process based on the size of a competitive window used in a process of former N continuous channel access failures, and resets the number of spare time slots to be detected according to the size of the currently used competitive window, thereby enabling the size of the competitive window to the increased according to an application scene and the needs, and reflecting the condition of a channel in real time. Moreover, the method flexibly resets the number of spare time slots to be detected according to the application scene, thereby improving the channel access probability, and effectively improving the channel access capability of LTE-U.