Grazing-incidence　X-ray　diffraction　measurements　(GIXRD)　were　performed　on　thin　films　of　SnO2　nanoparticles　coating　on　the　TiO2-nanotube　arrays　using　a　common　X-ray　diffractometer　with　focusing　light,　Shimadzu　XRD-7000.　By　GIXRD　analysis,　the　phase　components　of　the　coating　on　titanium　oxide　nanotube　arrays　were　disclosed,　and　a　multi-layer　structure　is　established:　SnO2　crystal　phase,　TiO　crystal　phase　and　amorphous　phase　with　SnO2　composition,　from　the　top　down,　respectively.　It　is　shown　from　the　GIXRD　results　that,　there　is　obvious　diffraction　peak　broadening　phenomenon　corresponding　to　the　decreasing　X-ray　incident　angles　(omega　＞=　2　degrees)　due　to　the　crystals　on　the　surface,　which　is　caused　by　the　nonparallel　X-rays　scattering　on　the　sample＇s　surface,　while　for　the　crystal　under　the　surface,　there　is　no　this　phenomenon　observed,　even　for　crystals　much　closer　to　the　surface.　This　provides　a　method　for　distinguishing　the　crystals　on　the　surface　or　under　the　surface.