激光在强湍流中的传输以及斜程传输问题是随机介质波传播研究中的热点，也是难点。文中尝试建立一个可以在任意湍流环境下通用的激光传输二阶矩演化模型。首先利用广义惠更斯-菲涅尔原理及球面波结构函数的二次近似推导了高斯-谢尔波束在大气湍流中传输时的互相干函数表达式。建立了波束互相干函数的三参数模型，得到了三参数的递进公式。利用三参数迭代法计算了部分相干波束在强湍流中及斜程传输时的等效波束半径及相干长度。计算结果证明了在强湍流中，相比于直接利用广义惠更斯-菲涅尔原理的计算结果，迭代法得到的等效半径较小，而相干长度较大。在斜程路径上，上行与下行传输激光的统计特性是不同的。

The problems of laser beam propagation in strong turbulence and the propagation along a slant path are hot and hard points in the subject of light propagation in random media. A model of the second-order moment of laser beam in any turbulence condition was elected. First the expression of the mutual coherent function was derived by using the extended Huygens-Fresnel principle. The model with three parameters for the second-order moment was created and the recursion formulas for the parameters were derived. The iteration formula of the parameters were used to calculated the effective beam radius and the length of coherence in the strong turbulence and in turbulence along a slant path. Compared with the results obtained by directly using the extended Huygens-Fresnel principle in strong turbulence, the effective beam radius obtained by the iteration formula is smaller and the corresponding coherence length is larger. The iteration method also shows that the characteristics of the uplink and downlink laser beam along a slant path are different.