【Abstract】 The reaction system of silver plating for micron copper particle was studied by SEM、 XRD and other testing means.It was found that micron copper particles produce stronger absorption to complex ions [Cu(NH3)4]2＋ which come from the substitution reaction. This absorption retards the substitution reaction so that Cu Ag bimetallic powders only with the plating of interspersion structure are obtained through once silver plating reaction. Besides, because of the plating of decoration structure a lot of minuteness cells form in the system, so that the plating changes into multilayer. Based on the mechanism,only if ions [Cu(NH3)4]2＋ absorbed are cleaned, the reaction of silver plating goes on in order to preparating Cu Ag bimetallic powders with the plating of packaging structure.更多还原