In single-beam transmission and reception free-space optical communication (FSO) systems, the intensity scintillation obeys the negative exponential distribution in weak turbulence while in strong turbulence it obeys logarithm normal distribution, which is universally accepted at present. Because the Gamma-Gamma distribution can describe both weak turbulence and strong turbulence, it becomes the hot spot recently. By extending them to multiple-beam transmission and reception FSO systems, the intensity scintillation′s probability density distribution functions are deduced and the channel models are established based on these distributions respectively. At last, the analysis of the influences of communication range, laser wavelength, receiving aperture as well as transmission and receiving antenna numbers on the channel model based on the negative exponential distribution and the simulations are detailedly done. All of these benefit theoretical research and design of the multiple-beam transmission and reception FSO systems.