A data transmission method is disclosed. The method in the embodiments of the present disclosure includes: obtaining, by a sending apparatus, a code block set; determining, by the sending apparatus, whether the code block set includes an idle code block; if the code block set comprises an idle code block, generating, by the sending apparatus, a dedicated code block, where the dedicated code block includes an indication field and a data field, the data field is used to carry a service, the indication field carries indication information, and the indication information is used to indicate that the dedicated code block and indicate that the data field carries the service; replacing, by the sending apparatus, the idle code block with the dedicated code block to obtain a target code block set, and sending, by the sending apparatus, the target code block set.