Taking　the　granite　residual　soil　embankment　of　Fujian　Province　as　an　example,　this　paper　investigated　the　moisture　migration　mechanism　in　granite　residual　soil　embankment　based　on　the　finite　difference　technology.　The　results　show　that　the　moisture　migration　of　the　shallow　layer　of　the　embankment　displays　up　first　and　down　later　in　dry　seasons.　In　rainy　seasons,　the　negative　pressure　head　of　the　embankment＇s　upper　soil　increases,　and　range　of　rainfall　variation　of　the　initial　period　is　much　sharper　than　the　later　period.　Meanwhile,　at　the　toe　of　slope,　the　rain　firstly　supplies　the　groundwater,　making　it　a　weak　location.　After　the　rain,　the　contour　line　of　negative　pressure　head　in　the　upper　embankment　gradually　becomes　sparse,　and　the　gradient　gradually　decreases　in　the　embankment.　The　fluctuation　of　negative　pressure　head　on　foundation　surface　decreases　with　the　depth　of　groundwater.　As　to　the　low　embankment,　the　change　of　the　embankment　moisture　mainly　depends　on　the　external　weather　conditions　when　the　groundwater　level　is　deep　and　the　moisture　is　mainly　affected　by　groundwater　when　the　groundwater　level　is　shallow.