A method of forming a silver catalyst layer in chemical plating includes providing a substrate; applying a silver-containing solution onto the substrate; and applying energy of activation to the silver-containing solution to form a silver catalyst layer over the substrate. The silver-containing solution includes silver ions, a diamine compound, a carboxylic acid compound, and a solvent. In addition, the substrate having the silver catalyst layer thereon can be immersed into a chemical plating solution to form a metal layer over the silver catalyst layer.