Designing　robust　visible　light-driven　photocatalysts　in　terms　of　the　structure　and　component　is　an　important　way　for　achieving　efficient　solar　hydrogen　production.　Herein,　Mo-doped　ZnIn2S4　(M-ZIS)　flower-like　hollow　microspheres　assembled　by　ultrathin　nanosheets　are　reported.　The　as-prepared　M-ZIS　samples　achieve　an　enhanced　H2　generation　rate　of　4.62　mmol　g−1　h−1　under　visible　light,　ten　times　higher　than　that　of　pristine　ZIS.　The　3D　hollow　microspheres　structure　assembled　by　nanosheets　ensures　sufficient　light　harvesting　and　exposure　of　more　active　sites.　Meanwhile,　the　doping　of　Mo　is　propitious　to　regulate　the　chemical　characteristic　and　electronic　structure　of　ZIS　in　the　merit　of　ameliorated　hydrophilicity,　extended　light　adsorption,　accelerated　transfer-separation　efficiency　of　charge　carriers,　as　well　as　the　reduced　overpotential　of　H2　evolution.　This　model　is　put　forward　to　obtain　an　in-depth　understanding　of　the　role　that　both　the　3D　hollow　hierarchical　structure　and　doping　atoms　play　in　photocatalytic　water　splitting.　©　2019　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim