Embodiments of the present invention provide a method and system for contending for a channel of an unlicensed frequency band, and an apparatus. The method for contending for a channel of an unlicensed frequency band in the present invention includes: acquiring, according to contention timeslot configuration information, a condition for starting a contention timeslot, and starting the contention timeslot when the condition is met, where the contention timeslot configuration information includes at least one of the following configurations: a time configuration of the contention timeslot, a contention backoff time, a terminal feedback uplink configuration, or a channel available condition; and performing a corresponding operation within the contention timeslot according to the time configuration of the contention timeslot to contend for a channel of an unlicensed frequency band, so as to implement data transmission on the unlicensed frequency band.