This application relates to the field of wireless communications technologies, and in particular, to a data processing method, apparatus, and system. This application provides a data processing method. A transmit device uses a sequence to carry data and a reference signal. The transmit device carries the two channels of data on an odd element and an even element of the sequence, respectively. The transmit device successively maps the sequence that carries the two channels of data to allocated subcarriers, and then sends the data in an orthogonal frequency division multiplexing (OFDM) manner. This application is intended to decrease cubic metric (CM)/peak-to-average ratio of a transmitted signal of an orthogonal frequency division multiplexing OFDM system through sequence design and mapping of the two channels of data to subcarriers, thereby improving link quality of an entire transmission system.