A Multiple Input Multiple Output(MIMO) optical wireless communication technology based on Discrete Multi-Tone/Quadrature Amplitude Modulation(DMT/QAM) and Space-Time Block Coding (STBC) is proposed in order to solve the problem of indoor diffuse optical wireless communication. Firstly, the channel model of indoor infrared wireless links is established based on DMT/QAM technique by considering the impulse response and noise characteristics of indoor all-optical wireless channel. Then, based on STBC technology, an MIMO wireless communication system for indoor diffuse optical wireless communication is proposed, and the important performance indicators, namely Signal-to-Noise Ratio(SNR) and Bit Error Rate(BER), at the receiver are obtained by analysis. The experimental results show that the proposed indoor MIMO optical wireless communication technology can not only reduce the BER for the system, but also obtain a better SNR compared with other traditional schemes, thus reducing the required optical transmitting power.