Numerous　researches　have　been　conducted　on　the　impacts　of　urban　thermal　environmental　factors　on　land　surface　temperature　(LST)　variations.　However,　few　have　comprehensive　studied　on　their　diurnal　variations.　This　study　explored　whether　the　novel　ECOSTRESS　LST　data　can　create　fresh　opportunities　for　analyzing　the　diurnal　urban　thermal　environment.　Here　we　utilized　ECOSTRESS　to　explore　the　relative　contribution,　marginal　effects,　and　granularity　effects　of　2D/3D　urban　factors　on　diurnal　LSTs　in　a　＂furnace　city＂　Fuzhou.　Our　results　revealed　that:　(1)　Anthropogenic　heat　flux　and　urban　blue　and　green　spaces　have　the　greatest　influence　on　nighttime　LST　and　daytime　LST,　respectively.　(2)　The　impacts　of　urban　factors　on　diurnal　LSTs　are　nonlinear.　The　marginal　effect　curve　can　reveal　the　crucial　value　ranges　and　turning　points　of　the　factors　that　affect　diurnal　LSTs.　(3)　The　overall　impact　of　the　2D　factors　on　diurnal　LSTs　is　more　significant　than　that　of　the　3D　factors.　Meanwhile,　3D　factors　are　indispensable　elements　in　urban　thermal　environment　research.　They　serve　as　an　important　supplementary　to　2D　factors　in　the　vertical　space　of　cities.　Our　findings　can　identify　crucial　factors　influencing　urban　thermal　environment,　providing　innovative　insights　for　the　development　of　strategies　to　mitigate　urban　heat　island　effects.