A channel detection method, applied to a wireless local area network device, characterized by comprising: measuring a channel before data are transmitted; and determining a Clear Channel Assessment, CCA, threshold according to a corresponding relation among a channel measurement result, transmitting power levels and channel access parameters, and judging whether a state of the channel is idle according to the CCA threshold; wherein the step of determining a Clear Channel Assessment CCA threshold according to a corresponding relation among a channel measurement result, transmitting power levels and channel access parameters, and judging whether a state of the channel is idle according to the CCA threshold, comprises: determining a corresponding channel access parameter according to a transmitting power level which is expected to be used; calculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the CCA threshold, and wherein, when it is judged that the state of the channel is busy according to the CCA threshold, the method further comprises: adjusting the transmitting power level which is expected to be used; determining a corresponding channel access parameter according to the adjusted transmitting power level which is expected to be used; recalculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the recalculated CCA threshold. measuring a channel before data are transmitted; and determining a Clear Channel Assessment, CCA, threshold according to a corresponding relation among a channel measurement result, transmitting power levels and channel access parameters, and judging whether a state of the channel is idle according to the CCA threshold; wherein the step of determining a Clear Channel Assessment CCA threshold according to a corresponding relation among a channel measurement result, transmitting power levels and channel access parameters, and judging whether a state of the channel is idle according to the CCA threshold, comprises: determining a corresponding channel access parameter according to a transmitting power level which is expected to be used; calculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the CCA threshold, and wherein, when it is judged that the state of the channel is busy according to the CCA threshold, the method further comprises: adjusting the transmitting power level which is expected to be used; determining a corresponding channel access parameter according to the adjusted transmitting power level which is expected to be used; recalculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the recalculated CCA threshold. determining a corresponding channel access parameter according to a transmitting power level which is expected to be used; calculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the CCA threshold, and wherein, when it is judged that the state of the channel is busy according to the CCA threshold, the method further comprises: adjusting the transmitting power level which is expected to be used; determining a corresponding channel access parameter according to the adjusted transmitting power level which is expected to be used; recalculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the recalculated CCA threshold. adjusting the transmitting power level which is expected to be used; determining a corresponding channel access parameter according to the adjusted transmitting power level which is expected to be used; recalculating a CCA threshold according to the channel access parameters and the channel measurement result; and judging whether the state of the channel is idle according to the recalculated CCA threshold.