The present invention provides a method and a device for data transmission. The method includes: according to a preconfigured second table, selecting a TBS value, where the second table is used for describing a corresponding relationship among a TBS value, the number of RBs and a TBS index, the number of RBs corresponding to the selected TBS value is smaller than or equal to a specific value, a modulation mode corresponding to a TBS index which corresponds to the selected TBS value is QPSK, and the selected TBS value is capable of satisfying the rate requirement required during transmission time interval TTI bundling transmission; and according to the selected TBS value, transmitting data carried by a PUSCH using bundled TTIs. The embodiments of the present invention can improve the coverage at a PUSCH medium data rate.