Pb2+　doped　Cd0.2Zn0.8S　and　Cd0.8Zn0.2S　were　prepared　with　coprecipitation　method.　The　results　indicate　that　the　valence　band　of　Cd0.2Zn0.8S　solid　solution　with　wide　band　gap　is　heightened　by　the　Pb　6s　level　hybridization　with　valence　band,　and　the　photocatalytical　hydrogen　evolution　ability　is　improved.　When　Pb2+　is　doped　in　Cd0.8Zn0.2S　solid　solution　with　narrow　band　gap,　it　acts　as　a　recombination　center　and　is　unable　to　improve　water　splitting　activity　of　the　catalyst.　So　the　doping　of　Pb2+　is　effective　only　for　the　semiconductor　with　wide　band　gap.