A　series　of　amorphous　Co-P　alloy　modified　ZnIn　2　S　4　composite　samples　were　synthesized　through　a　one-step　photochemical　method.　The　as-prepared　samples　were　systematically　characterized　and　the　photocatalytic　activity　for　H　2　production　under　visible-light　irradiation　was　investigated.　It　was　found　that　the　Co-P/ZnIn　2　S　4　composite　samples　exhibited　higher　photocatalytic　activity,　which　is　44　times　higher　than　that　of　pure　ZnIn　2　S　4　and　higher　than　that　of　the　1　wt%　Pt/ZnIn　2　S　4　sample.　After　modifying　with　amorphous　Co-P　alloy,　the　composite　samples　showed　enhanced　photocurrent,　reduced　photoelectric　impedance,　weakened　fluorescence　intensity　and　extended　fluorescence　lifetime,　which　accelerate　the　separation　and　transfer　of　photoinduced　charge　effectively,　thus　improving　the　catalytic　activity　of　the　composite　sample.　This　work　could　provide　a　new　strategy　for　the　design　and　synthesis　of　low-cost,　high-efficiency　composite　materials　for　photocatalytic　hydrogen　evolution　and　is　promising　for　energy　conversion　and　utilization.　©　2018　The　Royal　Society　of　Chemistry.