The present disclosure relates to precoding vector indicating and determining methods and communications apparatus. In one example method, a terminal device generates first indication information, and sends the first indication information to a network device. The first indication information is used to indicate one or more frequency domain vectors and one or more weighting coefficients, where the one or more frequency domain vectors include a frequency domain vector reported for each of R frequency domain unit groups, the one or more weighting coefficients include a weighting coefficient reported for each of the R frequency domain unit groups, and a frequency domain vector and a weighting coefficient that are reported for an rth frequency domain unit group in the R frequency domain unit groups are used to construct a precoding vector corresponding to one or more frequency domain units in the rth frequency domain unit group.