A pairwise maximum likelihood (ML) receiver is proposed for flip/unipolar orthogonal frequency division multiplexing (Flip/U-OFDM) system in visible light communication (VLC). Parts of Flip/U-OFDM signal are set at zero by pairwise ML in time domain, which can get some signal to noise ratio (SNR) gain. And the pairwise ML is a simple signal processing method, which will not increase the complexity for the receiver. Simulation results show that SNR gain of 2 dB can be available for the pairwise ML receiver in additive white Gaussian noise (AWGN) channel. SNR gain of 2 dB-3 dB will be achieved for the pairwise ML receiver in amplitude clipping channel and light emitting diode (LED) nonlinearity channel.