Embodiments of this application provide a communication method and an apparatus. A correspondence between a plurality of MCS indexes and a plurality of modulation schemes is provided to achieve flexible selection of a modulation scheme. In the correspondence, at least one MCS index of the plurality of MCS indexes corresponds to a set modulation schemes which comprises π/2 binary phase shift keying (π/2-BPSK) modulation and quadrature phase shift keying (QPSK) modulation. A first communication device receives a target modulation and coding scheme (MCS) index from a second communication device, determines a target modulation scheme corresponding to the target index number based on the correspondence, and performs communication with the second communication device based on the target modulation scheme.