为了研究大气激光通信中单模光纤耦合接收效率起伏概率分布特性，建立了受大气湍流扰动的瞬态耦合效率计算模型，据此得出影响光纤耦合效率统计分布的最少无量纲参数。通过研究发现：随着孔径半径-大气相干长度比的增大，耦合效率逐渐减小；随着耦合几何参数的增大，耦合效率先增大后减小，在某一点取得最大值。通过对空间光到单模光纤的瞬态耦合效率进行蒙特卡罗模拟与分布特征分析，提出使用双Johnson S_B分布来拟合瞬态耦合效率的概率密度函数，并用实验测量数据进行了验证。研究结果可以为不同大气湍流条件下的空间光到单模光纤耦合系统参数优化设计提供参考，有助于实现光纤耦合的大气激光通信系统。

To study the probability distribution characteristics of a single-mode fiber coupling's receiving efficiency fluctuations during atmospheric laser communication, a calculation model of transient coupling efficiency disturbed by atmospheric turbulence was established, and the least dimensionless parameters affecting the statistical distribution of the fiber coupling efficiency were obtained. The results show that as the ratio of aperture radius to atmospheric coherence length increases, coupling efficiency decreases, whereas when coupling geometry parameters increase, coupling efficiency increases initially before decreasing, indicating a single maximum point.The transient coupling efficiency of space light to single-mode fiber was simulated using the Monte Carlo method and analyzed using the distribution characteristics. The dual Johnson S_B distribution method was proposed to fit the probability density function of the transient coupling efficiency, and it was verified by the experimental data.The present results can provide references for optimized space-light parameter design in a single-mode fiber coupling system under different atmospheric turbulence intensities, supporting the realization of atmospheric laser communication systems with fiber coupling.