A first device, comprising: a receiving module, configured to receive a reference signal from a second device; a processing module, configured to obtain a precoding matrix based on the reference signal received by the receiving module, and generate first channel information and second channel information that are used to indicate the precoding matrix; and a sending module, configured to send the first channel information and the second channel information to the second device, wherein precision of the first channel information is higher than precision of the second channel information; and the first channel information comprises phase information of each element in the precoding matrix, and the second channel information comprises amplitude information of each element in the precoding matrix, characterized in that the processing module is specifically configured to generate the first channel information that comprises K groups of first channel sub-information, wherein K is a positive integer and is a quantity of column vectors comprised in the precoding matrix, and each column vector is corresponding to one group of first channel sub-information; and the first channel sub-information comprises: basic first channel sub-information, wherein the basic first channel sub-information is phase information of a reference element in a column vector corresponding to the first channel sub-information, and a phase of the reference element is non-zero; and L-2 pieces of relative first channel sub-information, wherein L is a length of the column vector, one piece of relative first channel sub-information is corresponding to one element whose phase is non-zero in the column vector other than the reference element, and is used to indicate a deviation between a phase of the corresponding element and the phase of the reference element; and the basic first channel sub-information is channel information that is unquantized, and the relative first channel sub-information is channel information that is quantized. a receiving module, configured to receive a reference signal from a second device; a processing module, configured to obtain a precoding matrix based on the reference signal received by the receiving module, and generate first channel information and second channel information that are used to indicate the precoding matrix; and a sending module, configured to send the first channel information and the second channel information to the second device, wherein precision of the first channel information is higher than precision of the second channel information; and the first channel information comprises phase information of each element in the precoding matrix, and the second channel information comprises amplitude information of each element in the precoding matrix, characterized in that the processing module is specifically configured to generate the first channel information that comprises K groups of first channel sub-information, wherein K is a positive integer and is a quantity of column vectors comprised in the precoding matrix, and each column vector is corresponding to one group of first channel sub-information; and the first channel sub-information comprises: basic first channel sub-information, wherein the basic first channel sub-information is phase information of a reference element in a column vector corresponding to the first channel sub-information, and a phase of the reference element is non-zero; and L-2 pieces of relative first channel sub-information, wherein L is a length of the column vector, one piece of relative first channel sub-information is corresponding to one element whose phase is non-zero in the column vector other than the reference element, and is used to indicate a deviation between a phase of the corresponding element and the phase of the reference element; and the basic first channel sub-information is channel information that is unquantized, and the relative first channel sub-information is channel information that is quantized. basic first channel sub-information, wherein the basic first channel sub-information is phase information of a reference element in a column vector corresponding to the first channel sub-information, and a phase of the reference element is non-zero; and L-2 pieces of relative first channel sub-information, wherein L is a length of the column vector, one piece of relative first channel sub-information is corresponding to one element whose phase is non-zero in the column vector other than the reference element, and is used to indicate a deviation between a phase of the corresponding element and the phase of the reference element; and the basic first channel sub-information is channel information that is unquantized, and the relative first channel sub-information is channel information that is quantized.