In the multiple-input multiple-output (MIMO) visible light communication (VLC) system, the effect of multipath can not be ignored specially at high bit rates. A modeling method for indoor multipath channel in VLC-MIMO system is proposed when there is the time dispersion at transmitter. A modeling method for indoor multipath channel in VLC-MIMO is proposed. Because the orthogonal frequency division multiplex (OFDM) can effectively resist inter-symbol-interference (ISI), the MIMO-asymmetrically clipped optical (ACO)-OFDM system is proposed by combing ACO-OFDM and MIMO techniques. The impulse response of each pair of LED and photoelectric detector（PD） is calculated by using recursive method. Then considering that the link between the centroid of LED and PD array is the equivalent line of sight (LOS) link, the multipath channel is established. The analysis results indicate that the gain of multipath channel is large and the multipath interference is weak when the PD arrays are at the center of the room, while the signal attenuation is large and the multipath interference is strong when the PD arrays are in a corner. The Monte Carlo bit-error-ratio (BER) simulation of MIMO-ACO-OFDM system are derived and modeled during both zero-forcing (ZF) and minimum mean square error (MMSE) signal detection. The BER performance degrades as the modulation order increases. When the modulation order is less than 64, the BER performance of ZF is worse than that of MMSE and the performance difference between ZF and MMSE decreases as the SNR increases. When the semi-angle at half power of LED becomes small, it has a better performance at the center of the room due to the strong beam convergence. Moreover, when the field of view (FOV) of LED becomes small, it has a better performance at the center of the room due to the decreased multipath interference, although the received power remains the same.