Embodiments of the present invention provide a data communication method and a related device. The data communication method may include performing, by a first communications device, power adjustment on Q codebooks using Q power factors, to obtain power-adjusted Q codebooks, where Q is a positive integer, and the Q power factors and the Q codebooks are in a one-to-one correspondence and mapping, by the first communications device, Q to-be-transmitted bit sequences to Q codewords in the power-adjusted Q codebooks, where the Q bit sequences and the Q codewords are in a one-to-one correspondence. The method also includes obtaining, by the first communications device, a modulation symbol based on the Q codewords and sending, by the first communications device, the modulation symbol on a resource block.