The present disclosure discloses an uplink retransmitted data sending method, apparatus, and system, and relates to the field of communications technologies. The method includes: receiving data transmitted on a same contention resource by different user equipments (UEs) that are in a same contention resource group; demodulating, based on a demodulation reference signal DMRS sequence carried in the data, the data sent by the UEs; and when demodulation of data sent by at least two UEs fails, scheduling, by using an uplink grant (UL-grant), the UEs whose data fails to be demodulated, to retransmit the data on a designated non-contention resource. This resolves a prior-art technical problem that uplink data retransmission fails, and improves uplink data retransmission efficiency.