A precoding matrix set determining method and apparatus, and a parameter indication information sending method and apparatus are provided. The precoding matrix set determining method include: determining, by a first network device, a parameter used for determining a precoding matrix set, where the parameter includes at least one of a phase parameter, an amplitude parameter, a quantity of vectors in the precoding matrix set, a quantity of vectors in a first codebook set in dual-codebook feedback, and a quantity of vectors in a second codebook set in the dual-codebook feedback, and the parameter is not fixed; and using the parameter to determine the precoding matrix set, where the precoding matrix set includes at least one precoding matrix. By using this solution, flexibility of feeding back a precoding matrix indicator is improved.