The　services　of　ecosystem　are　critical　to　human　existence　and　prosperity,　providing　necessary　ecological　products　for　human　production　and　life　as　well　as　indispensable　natural　conditions　for　life　system.　The　Natural　Mangrove　Reserve　in　Zhangjiang　River　Estuary　is　one　of　the　most　important　National　Natural　Mangrove　Reserve　in　China.　Its　environment　has　been　degrading　during　the　past　decades　for　people　neglecting　the　ecosystem　services　function　value　which　is　hard　to　currency　turn.　Thus,　it　is　necessary　to　monitor　and　assess　the　Mangrove　Reserve＇　dynamics,　both　to　gain　a　better　understanding　of　their　basic　biology　and　to　help　guide　conservation　and　restoration　efforts.　Using　Landsat　TM　Satellite　data　acquired　in　1989,　1998　and　an　Aster　image　from　the　year　2003,　the　land　use　of　the　Reserve　and　its　environment　were　extracted　adopting　the　supervised　Maximum　Likelihood　Classification　Algorithm.　The　changes　of　land　use　and　ecosystem　services　value　were　analyzed　using　Costanza＇s　method　of　evaluating　the　global　ecosystem　service　values.　The　total　value　change　of　ecosystem　services　was　-4.66×　104$　per　year　during　the　periods　of　1989-1998,　and　it　aggravated　to　-34.65×104$　during　the　periods　of　1998-2003.　The　results　indicate　that　the　ecosystem　services　value　in　the　study　area　has　been　constantly　deteriorating　due　to　the　human　activities　imposed　on　it,　which　is　highly　associated　with　the　local　expanding　of　build-up　and　brackish　water　fishponds　all　the　while.　And　the　downward　trend　of　the　ecosystem　services　value　has　become　even　more　acute,　with　the　development　of　the　local　economy.　©　2007　IEEE.