The FSO-OFDM (Free Space Optical Communication-Orthogonal Frequency Division Multiplexing) model based on light polarization is designed. We expatiated on the principles of the transceivers and the scatter channel. As the scatter channel is a frequency selective fading channel, each subchannel impulse response keeps correlation during coherent time. The correlation of the same subchannel impulse response is utilized during seriate OFDM symbols and Linear Mean Squared (LMS) algorithm is adopted to estimate the iterative initial value of the future symbols, then to get the channel impulse response. The horizontal and vertical polarization light paths are the same, so the characteristics of atmosphere channel are the same. At last, the more accurate channel impulse response is gotten after weighting the two estimative channel impulse responses. The simulation results indicate that the LMS algorithm can track the channel and get 2dB improvement of system BER.