For the problem of low communication capacity and low confidentiality of radio frequency(RF) communication, combined RF system and multiple input multiple output free-space optical(MIMO-FSO) system, this paper proposes the RF/MIMO-FSO hybrid communication system. Based on the analysis of RF system, MIMO-FSO system, single input single output (SISO)-FSO system and RF/MIMO-FSO hybrid communication system models, the bit error performance of the these four systems is compared through simulation. The result shows that compared with RF system and SISO-FSO system, the bit error performance of RF/MIMO-FSO hybrid communication system is significantly improved, it is about 3 orders of magnitude higher than SISO-FSO system on average under adopting the same modulation mode.