An uplink data transmission method and apparatus for latency reduction and a communications system. The uplink data transmission method includes: receiving resource indication information transmitted by a base station; the resource indication information indicating availability of using the semi-persistent resources at one or more TTIs or subframes by the first UE; determining a transmission resource from the semi-persistent resources according to the resource indication information when uplink data is needed to be transmitted; and transmitting the uplink data by using the transmission resource. Hence, not only latency of the uplink data may be reduced outstandingly, but also the semi-persistent resources may be allocated to other UEs with no waste of semi-persistent resources as much as possible, thereby improving resource utilization efficiency and transmission latency performance of the UE.