Hydrogen　can　be　produced　by　photoelectrochemical　(PEC)　water　splitting　using　a　KOH　solution　as　an　electrolyte　and　TiO2　as　a　photoanode.　In　this　work,　we　fabricated　anatase　TiO2　nanoring/nanotube　arrays　and　TiO2　nanotube　arrays　using　an　anodic　oxidation　method,　confirmed　by　field-emission　scanning　electron　microscopy　(FESEM)　and　X-ray　diffractometry　(XRD),　and　then　conducted　the　photoelectrochemical　experiments　with　1　M　KOH　and　Na2SO4　solutions.　The　bias　voltage,　small　impedance,　negative　flat-band　potential,　large　capacitance,　and　depletion　layer　width　in　the　anatase　TiO2-KOH　system　were　observed,　leading　to　the　stable　and　large　photocurrent　density.　To　understand　the　effects　of　KOH　on　the　interface　properties　of　TiO2/H2O,　the　electric　double　layers　of　anatase　TiO2(001),　(100),　(101)/KOH　interfaces　were　further　investigated　by　calculating　the　ion-surface　interaction　with　molecular　dynamics　simulations.　It　is　noted　that　the　number　density　of　potassium　ions　has　the　same　trend　as　that　of　oxygen　atoms　due　to　the　layering　effect　in　liquids　and　the　strongest　ionic　hydration　of　K+　on　anatase　(101)　is　observed　by　analyzing　the　radial　distribution　function　and　coordination　number.　In　addition,　the　electrostatic　characteristics　along　the　TiO2/KOH　interfaces　were　analyzed　based　on　the　Grahame　double　layer　model.　The　potential　drops　in　the　outer　Helmholtz　layer　of　anatase　(001),　(100),　and　(101)　surfaces　are　1.08,　0.26,　and　0.51　V,　respectively.　Compared　with　TiO2-H2O　systems,　the　larger　potential　drops　in　the　TiO2-KOH　system　explain　the　phenomenon　that　KOH　solute　contributes　substantially　to　a　chemical　bias　in　PEC　reactions.　At　the　same　time,　we　estimated　the　depletion　layer　widths　of　anatase　TiO2(001),　(100),　and　(101)　surfaces　as　37.48,　173.25,　and　64.49　angstrom,　respectively,　which　are　of　similar　magnitude　to　the　experimental　results.　Anatase　TiO2(100)　with　the　widest　depletion　layer　is　suggested　in　photocatalysis.　These　works　provide　a　clear　understanding　of　interfacial　behavior　of　KOH　on　anatase　TiO2　from　a　microscale,　which　can　be　used　to　explain　the　promotion　effect　of　the　KOH　electrolyte　and　guide　the　design　of　TiO2　nanocrystals　in　the　PEC　system.