A method for receiving an optical orthogonal frequency-division multiplexing (OFDM) signal and a receiver thereof are applicable to an optical OFDM system. The receiving method includes the following steps. An optical signal is converted into a digital signal. A symbol boundary of the digital signal is estimated. A guard interval of the digital signal is removed according to the symbol boundary, so as to generate an electrical signal. The electrical signal is converted into a plurality of frequency domain sub-carriers in a fast Fourier transform (FFT) manner. A timing offset is estimated with pilot carriers and frequency domain sub-carriers corresponding to the same symbol period. The estimated symbol boundary is compensated with the timing offset. Each frequency domain sub-carrier includes a plurality of pilot carrier signals. Through the receiving method, the timing offset arisen from chromatic dispersion of an optical fiber is effectively estimated and adopted for compensation.