A data transmission method includes generating a first code block, where the first code block includes a first load and a first redundancy code, the first load includes N second code blocks, the first redundancy code is used to perform error correction on the first load, an ith second code block includes a second load and a second redundancy code, the second redundancy code is used to perform error detection on the second load in the ith second code block, a value of i is an integer ranging from 1 to N, and Nis an integer greater than or equal to 1; and sending the first code block to a receive end.