A data transmission method, comprising: determining, by a base station, a data transmission resource, wherein the data transmission resource is less than a length of one subframe or is less than 1 ms in time domain; sending, by the base station, DCI to a terminal device, wherein the DCI is used to indicate the data transmission resource; and performing, by the base station, data transmission with the terminal device on the data transmission resource; wherein the data transmission resource comprises a time-domain transmission resource for downlink data transmission; and the determining, by the base station, the data transmission resource comprises: determining, by the base station, a starting symbol and a quantity of symbols of the time-domain transmission resource, and the DCI is used to indicate the starting symbol and the quantity of symbols of the time-domain transmission resource; wherein the DCI includes information used to indicate the downlink data transmission; and a reference symbol is used as the starting symbol of the time-domain transmission resource, and the reference symbol is the first symbol occupied by the DCI, the last symbol occupied by the DCI, the k th symbol following the first symbol occupied by the DCI, or the k th symbol following the last symbol occupied by the DCI, and k is a positive integer. determining, by a base station, a data transmission resource, wherein the data transmission resource is less than a length of one subframe or is less than 1 ms in time domain; sending, by the base station, DCI to a terminal device, wherein the DCI is used to indicate the data transmission resource; and performing, by the base station, data transmission with the terminal device on the data transmission resource; wherein the data transmission resource comprises a time-domain transmission resource for downlink data transmission; and the determining, by the base station, the data transmission resource comprises: determining, by the base station, a starting symbol and a quantity of symbols of the time-domain transmission resource, and the DCI is used to indicate the starting symbol and the quantity of symbols of the time-domain transmission resource; wherein the DCI includes information used to indicate the downlink data transmission; and a reference symbol is used as the starting symbol of the time-domain transmission resource, and the reference symbol is the first symbol occupied by the DCI, the last symbol occupied by the DCI, the k th symbol following the first symbol occupied by the DCI, or the k th symbol following the last symbol occupied by the DCI, and k is a positive integer. determining, by the base station, a starting symbol and a quantity of symbols of the time-domain transmission resource, and the DCI is used to indicate the starting symbol and the quantity of symbols of the time-domain transmission resource; wherein the DCI includes information used to indicate the downlink data transmission; and a reference symbol is used as the starting symbol of the time-domain transmission resource, and the reference symbol is the first symbol occupied by the DCI, the last symbol occupied by the DCI, the k th symbol following the first symbol occupied by the DCI, or the k th symbol following the last symbol occupied by the DCI, and k is a positive integer.