The invention discloses a data transmission method, including the following steps: (1) processing error correction treatments to the data packets to be transmitted to generate error correction packets; (2), encapsulating all the data packets and all the error connection packets in different multiplex adaptive transmission packets by adopting the same data packet identifier; (3), multiplexing the multiplex adaptive transmission packets into multiplex frames for transmission. Through the method and the device, the data of the source file and the error-corrected coded data can be transmitted at the same time and are ensured to be received correctly by a terminal.