在对ｒｆ一溅射制得的掺ＳｎＯ２和Ｉｎ２Ｏ３薄膜（ＩＴＯ）的电性能进行测量时，发现样品的方块电阻（Ｒ□）经热处理后明显下降．为此我们用ＴＥＭ对薄膜的显微结构进行了动态观察，在观察的过程中随电子束的轰击发现有多晶化转变，即在电子束轰击后薄膜由主要以非晶态构成的结构变成了主要为平均晶粒尺寸约５０ｎｍ的多晶态结构．本文对这一薄膜显微结构的变化与其电性能之间的关系进行了详细地讨论． When the electrical properties of SnO2 and In2O3 films doped with ITO were measured, the sheet resistance (R D) of the samples was found to decrease significantly after heat treatment. To this end, we used TEM to observe the microstructure of the film. In the process of observation, we found that there is polycrystallization transition with the electron beam bombardment. That is, the structure of the film is mainly composed of amorphous state after electron beam bombardment A polycrystalline structure mainly having an average grain size of about 50 nm has been formed. This paper discusses the relationship between the changes in the microstructure of the film and its electrical properties in detail.