From the light-emitting diode (LED) Shockley equation, a LED′s bidirectionally saturated nonlinearity model in visible light communication (VLC) system is established in conjunction with high power amplifier model which shows saturated behavior at very large input voltage. Monte Carlo simulations are conducted to an orthogonal frequency division multiplex (OFDM) based VLC system using the LED model. Manifold analyses suggest that the system performance deeply depends on some key parameters in respect of LED nonlinearity, direct current (DC) bias voltage, baseband modulation scheme, signal clipping ratio, and the manner in which the signal is clipped.