The structural changes and the morphology of the evaporated Au-11.4 wt%Ge-4.8 wt%Ni films during heating have been studied by TEM. The structure of the as-evaporated film is a supersaturated Au solid solution and after more than 10 minutes anealling above 300℃ the film decomposes into Au solid solution and NiGe compound. In-situ observations in the heating stage of HVEM have revealed that the NiGe grains with size near 2000 A are dissolved into the Au solid solution in 2 seconds during heating to about 500℃. The remaining NiGe grains in the film prevent the balling process of the Au solid solution films occuring above 500℃.