A channel access method and a node are disclosed. The method includes randomly selecting a backoff period XB according to a backoff exponent BE, where XB=X×aUnitBackoffPeriod, and X is an integer randomly selected from 0−(2BE−1); when X is greater than or equal to a predetermined value, determining a middle backoff, where the middle backoff is less than the backoff period, performing a backoff until the middle backoff ends and then performing a CCA; if a channel is clear, performing data transmission, and if the channel is not clear, continuing the backoff until the backoff period ends and then performing a CCA, and executing a channel access operation according to a result of the CCA performed when the backoff period ends. Therefore, data transmission is performed when a channel is clear, which can reduce a data transmission delay.