本文采用固定入射角，改变入射光偏振方位角的方法从实验上研究了锗薄膜的透射光学二次谐波产生及其变化规律．并从理论上推导了产生透射二次谐波的表达式。最后拟合求得描述面谐波电流的唯象参数ａ． In this paper, the method of fixed angle of incidence and changing the azimuth angle of incident light were used to study the generation and variation law of transmitted second harmonic of germanium thin film. The expression of the second harmonic generation is derived theoretically. The last fitted to obtain the phenomenological parameters describing the surface harmonic current a.