This application discloses a signal transmission method. The method includes: mapping, to M evenly spaced subcarriers, each of a first sequence including M elements and a second sequence including M elements, where the M subcarriers are subcarriers on a same time domain symbol, the first sequence and the second sequence are code division-orthogonal, the first sequence a0, a1, . . . , aM-1 is obtained by extending a third sequence c0, c1, . . . , cK-1 having a length of K, and the second sequence b0, b1, . . . , bM-1 is obtained by extending a fourth sequence d0, d1, . . . dK-1 having a length of K, where M=p×K, i is a variable, a value of i is 0, 1, . . . , M−1, u and v each are one of 0, 1, . . . , p−1, and v is not equal to u; generating a to-be-sent signal based on elements on the M subcarriers; and sending the to-be-sent signal.