Abstract: In this letter, we derive an exact and approximate equation of spatial correlation based on Laplaciian energy distribution,and analyze the factors which have the effect on saptial correlation and use the results into the analysis of the BER performance of MIMO system. We analyze them in the uniform liner array (ULA) and uniform circular array (UCA) respectively, in which we present relationships of the BER versus the SNR, distance between antennas, and the angle of arrival (AOA) with different decay factors. And we also analyze the factors that determine the BER of the system, and the method of reducing the BER. Finally, when the value of decay factor a is big, the approximate analysis exhibits good agreement with the exact analysis, and makes the computational complexity greatly simplified.