Water　adsorption　capacity　is　a　key　factor　to　influence　photocatalytic　H2　evolution　activity　for　polymeric　g-C3N4.　Herein　we　report　the　synthesis　of　3D　ordered　close-packed　g-C3N4　nanosphere　arrays　(CNAs)　to　significantly　enhance　its　water　adsorption　capacity.　Through　precisely　controlling　the　average　stacking-layer-number　(ASLN)　of　nanospheres　in　CNAs,　we　reveal　an　interesting　stacking-layer-number　dependence　of　water　adsorption　in　the　newly　designed　CNAs　in　accelerating　H2　evolution　reaction,　which　can　be　attributed　to　the　differences　in　adsorption　surface　areas　and　adsorption　sites　endowed　by　the　point　defect　cavities　in　samples　CNAs.