Embodiments of the present invention provide a data transmission method, a base station, and a user equipment. The data transmission method includes: determining, by a base station, a modulation and coding level and a time-frequency resource, and determining, in a first or second modulation and transport block size index table, a TBS index and a modulation mode, where a second TBS index is not smaller than a first TBS index; and sending service data and a system scheduling control signal to a user equipment by adopting the selected TBS. In this way, the base station can select a larger TBS to achieve a higher coding rate and increase a system throughput.