Abstract:The selection of etchant and the analysis of grain are the key to test method of grain of Cu Ag alloy. The results show that etchant composed of a mixture of 2g ferric nitrate and 50mL anhydrous ethanol is suitable for displaying the grains of Cu-0.1% Ag alloy.The grain boundary of metallographic structure is clear and the grains are complete. The microstructure of the alloy is mainly composed of single-phase Cu solid solution, and equiaxed grains, crystal twin, columnar grains and fibrous tissue appear, which is closely related to the properties of the alloy.