Most present researches of FSO system are based on the assumption of plane wave or spherical wave,while the actual transmitting beam of FSO system is Gaussian beam, so the study of the effect of different transmitting beam on the performance of FSO system is important. Starting from the aperture averaging effect, without considering the impact of the turbulent inner and outer scale, the effect of turbulent strength on the aperture averaging effect is analyzed under the Gaussian beam condition. It's shown that the aperture averaging effect is more obvious by increasing the turbulent strength. And then,under the weak turbulent condition, the effect of transmitting beam on the improvement of BER performance by aperture averaging effect is simulated. The results show that Gaussian-beam wave has the most apparent impact on BER performance,and saturation occurs first,followed by spherical wave. Plane wave is relatively gentle.%在无线光通信中,研究通信系统性能时多数是在平面波、球面波条件下进行的,而实际无线光通信系统发射的激光是高斯波束,所以研究不同波束对通信系统性能的影响具有重要意义.本文从孔径平均效应出发,运用理论分析和实验仿真的方法,在不考虑湍流内、外尺度影响的前提下,首先描述了高斯波束条件下,孔径平均因子随孔径尺寸的变化趋势,并且比较了不同湍流强度条件下孔径平均效应的差异；在OOK调制和非相干检测条件下,比较不同传输波束在弱湍流大气中传输时,孔径平均在改善误码率性能方面存在的差异.结果表明:高斯波束对误码率的影响明显,最先达到饱和状态,球面波次之,平面波较为平缓.
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