A communication method includes: A first device receives a plurality of NDPs from a second device, where one of the plurality of NDPs corresponds to one piece of CSI; and when a first condition is met, the first device sends first information to a third device, where the first information indicates that a CSI change degree exceeds a first threshold; and the first condition includes any one of the following: a first CSI change degree in a plurality of CSI change degrees of the first device exceeds the first threshold, and a ratio of a quantity of CSI change degrees that exceed the first threshold in the plurality of CSI change degrees to the plurality of CSI change degrees is greater than a second threshold, where the plurality of CSI change degrees are determined based on pieces of CSI corresponding to the plurality of NDPs.