As　cocatalysts　play　important　roles　in　enhancing　the　catalytic　performance,　designing　and　fabricating　highly　active　cocatalysts　is　an　effective　approach　to　improving　photocatalytic　H-2　production.　In　this　work,　transition　metal　phosphides　(including　Fe2P,　Co2P,　and　Ni2P)　with　nanoscale　structures　are　synthesized　by　the　solvothermal　method,　which　can　largely　enhance　the　photocatalytic　activity　and　stability　of　CdS　nanorods　as　cocatalysts.　By　optimizing　the　synthesis　and　reaction　conditions,　10%　Co2P/CdS　achieved　the　highest　H-2　production,　about　29.24　mmolg(-1)h(-1)　in　the　lactic　acid　solution,　which　was　21.5　and　3.0　times　higher　than　that　of　CdS　(1.36　mmolg(-1)h(-1))　and　1%　Pt/CdS　(9.63　mmolg(-1)h(-1)),　respectively.　Testing　by　many　characterizations,　not　only　the　reasons　for　different　activities　for　TMPs/CdS　but　also　the　enhanced　reasons　of　Co2P/CdS　are　explored.　The　results　indicated　that　the　non-noble　metal　Co2P　cocatalyst　not　only　enhanced　the　visible　light　absorption　of　CdS　but　also　promoted　the　effective　separation　of　photogenerated　charge　carriers.　This　work　contributes　to　the　further　development　of　TMPs　as　low-cost　and　highly　active　cocatalysts　for　CdS-based　photocatalysts.