Disclosed are a channel detection apparatus and method, as well as a user equipment and a base station comprising the channel detection apparatus. The channel detection apparatus is used for performing channel detection over a plurality of carriers in an unlicensed frequency band, and comprises at least one processing circuit. The plurality of carriers comprise a first carrier and a second carrier. The processing circuit is configured to: perform channel detection of whether a channel is idle on the first carrier; and trigger, when it is detected that the channel is occupied during the channel detection on the first carrier, channel detection of whether a channel is idle on the second carrier.