This application provides a symbol processing method and related apparatus. The method includes: dividing a plurality of obtained complex-valued symbols into a plurality of sets, where each set corresponds to one transmit symbol, and the plurality of sets include a first set corresponding to a first transmit symbol; and mapping a first sequence and a second sequence to the first set, where an end position of the first sequence is a position of intercepting a cyclic prefix (CP) in the first transmit symbol, and an end position of the second sequence is an end position of the first transmit symbol. By mapping the sequences to the sets, an original cyclic prefix (CP) can be extended using a sequence with a flexible length, and flexible guard periods of different lengths can be configured for different users by adjusting the length of the sequences.