Embodiments provide a data transmission method, a base station and user equipment. The method includes: selecting one MCS table from at least two modulation coding scheme MCS tables to determine an MCS, and selecting one TBS table from at least two transport block size TBS tables to determine a TBS, where at least one MCS table of the at least two MCS tables includes an MCS corresponding to 256 quadrature amplitude modulation QAM; and sending service data to user equipment based on the determined MCS and the determined TBS. Frequency spectrum efficiency of the system can be maximized and a system throughput can be improved.