Since　China＇s　reform　and　opening-up,　the　rapid　growth　of　China＇s　economy　has　greatly　accelerated　the　expansion　of　built-up　land,　which　has　affected　regional　ecological　environment　to　a　great　extent.　Taking　Jinjiang　County　of　Fujian　Province,　one　of　the　fastest　economic-developing　counties　in　the　coastal　areas　of　southeastern　China,　as　a　case　study　area,　this　paper　focused　on　analyzing　the　rapid　built-up　land　expansion　process　of　the　county　and　its　impact　on　county＇s　ecological　quality　using　remote　sensing　techniques.　Based　on　two　Landsat　images　of　1996　and　2015　of　Jinjiang,　the　built-up　land　of　the　county　was　extracted　using　the　index-based　built-up　index　(IBI)　and　its　change　was　analyzed.　In　the　meantime,　the　ecological　status　of　Jinjiang　was　evaluated　with　a　recently-proposed　remote　sensing　based　ecological　index　(RSEI)　and　the　relationship　between　the　built-up　land　dynamics　and　the　ecological　status　changes　of　the　county　was　quantitatively　examined.　The　results　showed　that　during　the　period　from　1996　to　2015,　the　area　of　built-up　land　of　Jinjiang　had　a　net　increase　of　68.54　km2,　a　growth　of　45%,　and　the　expansion　intensity　was　0.55.　The　expansion　of　the　built-up　lands　has　caused　overall　degradation　of　the　county＇s　ecological　quality.　The　mean　value　of　RSEI　of　the　county　had　declined　from　0.532　in　1996　to　0.460　in　2015,　a　drop　of　13.5%.　The　area　proportion　of　high　ecological-quality　grades　also　significantly　fell　from　39%　in　1996　to　21%　in　2015.　The　built-up　land　expansion　intensity　was　negatively　correlated　with　the　ecological　quality　change.　©　2017,　Science　Press.　All　right　reserved.