An uplink transmission method based on a licensed-assisted access (LAA) system, and an apparatus, where the method includes reserving, for a transmission burst transmitted on an unlicensed carrier, at least one single-carrier frequency-division multiple access (SC-FDMA) symbol in a subframe of an uplink transmission burst corresponding to the transmission burst, where in the reserved at least one SC-FDMA symbol, user equipment (UE) accesses a channel using a listen-before-talk (LBT) access mechanism. Hence, a time gap for accessing the channel through LBT can be reserved for another UE in the uplink transmission burst. This improves a probability of successfully accessing the channel by another UE such that a plurality of UEs in an LAA communications system can perform uplink multiplexing.