To　protect　the　data　confidentiality　of　Android　device　users,　this　paper　proposed　a　user-level　secure　data　sanitization　method　which　can　make　sensitive　data　stored　in　flash　memory　unrecoverable.　The　proposed　method　using　reversed-scanning　algorithm　to　reduce　time　and　it　don＇t　need　overwriting　or　erase　the　whole　flash　memory.　After　sensitive　data　pages　are　found,　the　program　targetedly　overwriting　some　blocks,　erase　them,　and　insert　them　into　free　block　list　waiting　to　be　located　again　which　means　the　blocks　will　be　twice　overwrited　by　new　data.　©　2015　SERSC.