A clear channel detection method includes: if a node device performs a CCA detection for the first time and finds that a full bandwidth of an unlicensed carrier channel is in a busy state, the node device divides the full bandwidth of the unlicensed carrier channel into two or more sub-bandwidths for the first time according to a preset division manner; if the node device performs the CCA detection again and finds that all sub-bandwidths are in the busy state, the node device divides each of the divided sub-bandwidths into two or more sub-bandwidths for the second time according to the preset division manner, and continues to perform CCA detection until the CCA detects that any sub-bandwidth is in a clear state, or the number of CCA cycle detections is up to a maximum value, then exits from the CCA cycle detections.