Disclosed in the present application are a data transmission method and a communication device. The method includes: obtaining transmission parameters for transmitting a transport block, wherein the transmission parameters comprise Modulation and Coding Scheme (MCS), a Physical Resource Block (PRB) number, and PRB resource overhead information; determining a Transport Block Size (TBS) for the transport block according to the transmission parameters; and transmitting the transport block or receiving the transport block according to the TBS; wherein the PRB resource overhead information is determined based on at least one of: Demodulation Reference Signal (DMRS), Channel State Information-Reference Signals (CSI-RS), and control channel information.