This application provides a method for detecting margins of a data signal. A receive end of a data signal may adjust a voltage of a reference power source; adjust, based on a plurality of reference moments included in a reference moment set, a moment of an edge of a data strobe signal transmitted by a transmit end of the data signal; and during the adjustment, for each reference voltage and each reference moment, determine whether a bit error exists in data obtained by decoding the data signal when the voltage of the reference power source is the reference voltage and the moment of the edge of the data strobe signal is the reference moment, to obtain a timing margin of the data signal at each reference voltage and a voltage margin of the data signal at each reference moment.