A data transmission method, an apparatus, and a system are disclosed, to resolve a problem that a transmission mechanism based on a transmission time interval TTI of one subframe or a transmission mechanism based on a TTI of 1 ms cannot satisfy a service latency requirement of a user. In a base station provided in embodiments of the present invention, a processor is configured to: determine a data transmission resource, where the data transmission resource is a short-TTI data transmission resource, and the short-TTI data transmission resource is less than a length of one subframe or is less than 1 ms in time domain; and a transceiver is configured to: send DCI to a terminal device, where the DCI is used to indicate the data transmission resource; and perform data transmission with the terminal device on the data transmission resource.