This application relates to a sequence detection method and a device. One example method includes receiving a first sequence carried on a plurality of subcarriers; differentiating the first sequence based on L granularities, to obtain a first differential sequence set comprising L sequences; determining K candidate frequency domain root sequences in the U candidate frequency domain root sequences based on differential sequence cross correlation value sets corresponding to the U candidate frequency domain root sequences; and determining a candidate frequency domain root sequence and a time domain cyclic shift value that correspond to the first sequence, based on the first sequence and the K candidate frequency domain root sequences.