CdS　QD-modified　TiO2　nanotube　arrays　were　fabricated　using　an　anodic　oxidation-sequential　chemical　bath　deposition　process.　By　means　of　FESEM,　EDS,　XRD　and　XPS,　it　could　be　confirmed　that　the　use　of　an　ultrasonication-assisted　deposition　approach　improved　the　distribution　of　CdS　QDs　on　the　tube　wails.　The　as-prepared　CdS-modified　TiO2　nanotube　arrays　exhibited　enhanced　photoelectrochemical　properties　and　hydrogen　production　activity,　which　benefitted　from　the　extended　light　absorption　and　the　improved　interfacial　charge-transfer　properties　of　TiO2　nanotube　arrays.　By　analyzing　the　interfacial　properties,　the　flatband　potential,　the　depletion　layer,　the　capacitance,　and　the　impedance　of　the　CdS/TiO2　photoelectrode,　it　can　be　concluded　that　compared　with　pure　TiO2　nanotube　arrays　the　CdS　QD-modified　arrays　exhibited　a　more　negative　flat　band　potential　and　a　lower　energy　barrier　for　interfacial　electron　transfer.　The　calculated　depletion　layer　width　(d(SC))　of　the　sensitized　TiO2　nanotube　arrays　was　larger,　which　under　a　sufficiently　high　applied　potential　could　facilitate　the　formation　of　a　completed　depletion　layer;　the　space-charge　capacitance　(depletion　layer　capacitance)　and　the　double-layer　capacitance　increased　with　the　CdS　QDs　modification,　and　the　impedance　and　charge-transfer　resistance　were　reduced.