The invention discloses an optical OFDM (Orthogonal Frequency Division Multiplexing) method capable of transmitting three paths of signals simultaneously. The method is characterized by comprising the following steps that: a transmitting end overlaps an ACO-OFDM (Asymmetrically Clipped Optical OFDM) signal and a DCO-OFDM (Direct Current Biased Optical OFDM) signal in sequence on a signal of conventional PAM-DMT (Pulse-Amplitude-Modulated Discrete Multitone); and a receiving end detects the PAM-DMT signal, the ACO-OFDM signal and the DCO-OFDM signal in sequence by using an interference relation among the three paths of signals, so that simultaneous transmission of the PAM-DMT signal, the ACO-OFDM signal and the DCO-OFDM signal is realized. Through adoption of the method, carrier resources of optical OFDM are fully utilized; the frequency utilization rate of a system is increased; meanwhile, only a small amount of direct current needs to be added; and good compromise between frequency spectrum effectiveness and power effectiveness is realized.