In this paper, the impacts of mutual coupling on the performance of MIMO wireless channel are analyzed. From the analysis of the antenna model by network equivalent analysis, the impedance matrix and the mutual coupling matrices of transmitter and receiver are obtained. A general expression of the spatial correlation between a pair of mutually coupled antennas is explicitly derived, and the conditions under which mutual coupling has no effect on the spatial correlation are also identified. The effects of mutual coupling on the parallel antenna array and the collinear antenna array are investigated. Simulation results show that the impacts of mutual coupling on parallel antenna array and collinear antenna array are quite different in the performance of MIMO channel, and the performance of MIMO system affected by mutual coupling can be improved effectively by properly selecting antenna array.