The　extraordinary　electrical　conductivity　of　graphene　has　been　widely　regarded　as　the　bible　in　literature　to　explain　the　activity　enhancement　of　graphene-semiconductor　composite　photocatalysts.　However,　from　the　viewpoint　of　an　entire　composite-based　artificial　photosynthetic　system,　the　significant　matter　of　photocatalytic　performance　of　graphene-semiconductor　composite　system　is　not　just　a　simple　and　only　issue　of　excellent　electrical　conductivity　of　graphene.　Herein,　the　intentional　design　of　melamine　resin　monomers　functionalized　three-dimensional　(3D)　graphene　(donated　as　MRGO)　with　significantly　deteriorated　electrical　conductivity　enables　us　to　independently　focus　on　studying　the　geometry　effect　of　MRGO　on　the　photocatalytic　performance　of　graphene-semiconductor　composite.　By　coupling　semiconductor　CdS　with　graphene,　including　MRGO　and　reduced　graphene　oxide　(RGO),　it　was　found　that　the　CdS-MRGO　composites　exhibit　much　higher　visible　light　photoactivity　than　CdS-RGO　composites　although　the　electrical　conductivity　of　MRGO　is　remarkably　much　lower　than　that　of　RGO.　The　comparison　characterizations　evidence　that　such　photoactivity　enhancement　is　predominantly　attributed　to　the　restacking-inhibited　3D　architectural　morphology　of　MRGO,　by　which　the　synergistic　effects　of　boosted　separation　and　transportation　of　photogenerated　charge　carriers　and　increased　adsorption　capacity　can　be　achieved.　Our　work　highlights　that　the　significant　matter　of　photocatalytic　performance　of　graphene-semiconductor　composite　is　not　a　simple　issue　on　how　to　harness　the　electrical　conductivity　of　graphene　but　the　rational　ensemble　design　of　graphene-semiconductor　composite,　which　includes　the　integrative　optimization　of　geometrical　and　electrical　factors　of　individual　component　and　the　interface　composition.　©　2015　American　Chemical　Society.