It　was　found　that　stannous　chloride　(SnCl2),　as　a　popular　inorganic　reducing　reagent,　could　obviously　enhance　the　electrochemiluminescence　(ECL)　of　tris(2,2＇-bipyridyl)　ruthenium(II)　(Ru(bpy)(3)(2+))　in　aqueous　solution.　Some　factors　affecting　the　ECL　reactions　between　Ru(bpy)(3)(2+)　and　Sn2+,　including　pH,　concentrations　of　coreactant,　and　electrode　materials,　were　investigated　by　comparison　with　a　classic　ECL　coreactant　tripropylamine　(TPA).　The　Ru(bpy)(3)(2+)-Sn2+　ECL　coreactant　system　produces　stronger　and　more　stable　ECL　signals,　can　keep　its　excellent　ECL　activity　over　a　wider　pH　range　and　has　more　choices　in　using　electrode　materials　than　the　Ru(bpy)(3)(2+)-TPA　ECL　coreactant　system.　The　ECL　mechanism　of　the　Ru(bpy)(3)(2+)-Sn2+　coreactant　system　was　also　studied　in　detail.