This　paper　took　Pingtan　County,　an　island-town　located　in　the　eastern　seashore　of　Fujian　Province,　as　the　study　area.　By　the　comprehensive　use　of　RS　and　GIS　techniques,　this　paper　summarized　the　morphological　characteristics　of　main-urban　area　spatial　expansion　in　Pingtan　County　since　the　Hercynian　construction　was　proposed.　The　expansion　characteristics　were　systematically　analyzed　by　introduced　three　indicators:　urban　sprawl　strength,　urban　center　and　compact　index.　Combined　with　regional　socio-economic　development,　this　paper　also　investigated　the　driving　mechanism　of　urban　land　growth　from　the　following　aspects,　geographical　environment,　population-driven,　economic　development,　macroeconomic　policy　and　urban　planning　guidance,　etc.　The　results　showed　that　it　was　quite　distinct　of　Pingtan　County　urban　spatial　expansion,　and　the　built-up　area,　increased　from　5.23　km2　in　2002　to　7.69　km2　in　2007,　had　risen　by　about　half　in　five　years;　the　growth　area　was　mainly　concentrated　in　eastern　and　southern　parts;　the　county　center　had　been　offset　by　220m　along　the　southeast　direction;　the　urban　space　expansion　was　a　combined　result　of　natural,　economic　and　social　factors.　©　2012　IEEE.