Examples of the present disclosure provide a data transmission method, a terminal device, a base station, and a system. The data transmission method includes: configuring, by a base station, first DCI for a terminal device, where the first DCI includes scheduling information used for data transmission; sending, by the base station, the first DCI to the terminal device; configuring, by the base station, second DCI for the terminal device, where the second DCI includes first information, and the first information includes information used to indicate the terminal device to perform transmission of a first data packet with the base station according to the first DCI; sending, by the base station, the second DCI to the terminal device; and performing, by the base station, transmission of the first data packet with the terminal device.