提出一种特征值方法用于计算具有流动饱和增益介质的气体激光器的光场分布情况。计算模型中，流动饱和增益介质等效为一个位于激光谐振腔内的大腔镜前面的薄增益片。基于这个模型，可以获得特征值法的传输矩阵。通过求解传输矩阵的特征值与特征向量，能够较容易地获得激光器谐振腔中所有可能存在的光场分布情况，通过比较它们的损耗参数能够获得激光器实际存在的光场分布。模拟计算结果显示：流动饱和增益介质对光场分布具有负面影响，它将导致光场分布沿着气体流动的方向倾斜。该方法的模拟计算结果能够与其它方法的模拟计算结果较好地吻合。

An eigenvector method(EM)is given to calculate the optical field in laser with flowing saturable gain media. Flowing staturable gain media is equivalent to a thin gain sheet just near inside the big mirror of laser resonators cavity. And transit matrix of EM is obtained on the basis of this model. The calculated results show that the flowing saturable gain media has a negative effect on the optical field distribution. It causes the optical field distribution inclines along the direction of gas flowing. The results are in good agreement with other methods.