We used aurous chloride and thiocyanate as raw materials, with method of " Selective reduction-complexation" , for the synthesis of " Au-thiocyanate" complex, and determined its molecular formula-NH₄[ Au ( SCN)₂] by elemental analysis. According to the relevant technology of PCB industry, chemical plating properties of the complexes were discussed, and we got the best process condition: pH = 2 ~ 5 , aurous concentration 1 ~ 3 g / L, temperature 40 ~ 60 ℃ , plating time 9 ~ 12min, respectively. Under this condition resulting gold layer thickness of 0 . 12 μm, which can meet the quality requirement of the related industries.