Controlling　the　crystallinity　and　microstructure　of　a　semiconductor　photocatalyst　serves　as　an　effective　means　to　boost　its　photocatalytic　performance　through　improving　the　charge　transfer　and　separation,　enhancing　the　light　absorption,　or　maneuvering　the　surface　reactions.　Nevertheless,　the　internal　pores　in　aerogel　materials　inevitably　collapse　during　the　traditional　high　temperature　crystallization　process,　significantly　reducing　the　porous　structure　and　specific　surface　area　(SSA).　Herein,　microsphere　ZnO　aerogels　have　been　successfully　fabricated　for　photoreduction　of　CO2　using　a　cooperative　strategy　of　sol-gel　method,　solvothermal　crystallization　and　cryodesiccation.　The　obtained　aerogel　has　a　large　SSA　and　high　crystallinity.　Compared　with　the　commercial　ZnO　powder,　the　ZnO　aerogel　microsphere　exhibits　about　4-fold　increase　in　specific　surface　area,　leading　to　an　increased　contact　surface　between　the　photocatalyst　and　the　reactant.　At　the　same　time,　ZnO　aerogel　with　microsphere　morphology　possesses　high　light-harvesting　and　intrapore　light　reflecting　capabilities,　demonstrating　enhanced　optical　utilization.　Modulation　of　the　crystallinity　of　ZnO　aerogel　facilitated　the　incorporation　of　defect　engineering　(zinc　defects　(Zni)　and　oxygen　vacancies　(Vo)).　As　a　result,　ZnO　aerogel　microsphere　exhibits　a　5-fold　higher　products　production　rate　than　ZnO　powder　for　photocatalytic　CO2　reactions　due　to　the　synergistic　effect　of　appropriate　crystallinity　and　microsphere　appearance.　It　is　hoped　that　this　work　may　provide　some　insights　to　tune　the　catalyst　performance　through　crystallinity　and　morphology.