World-wide　urbanization　has　significantly　modified　the　landscape,　which　has　important　climatic　implications　across　all　scales　due　to　the　simultaneous　removal　of　natural　land　cover　and　introduction　of　urban　materials.　This　resulted　in　a　phenomenon　known　as　an　urban　heat　island(UHI).　A　study　on　the　UHI　in　Xiamen　of　China　was　carried　out　using　remote　sensing　technology.　Satellite　thermal　infrared　images　were　used　to　determine　surface　radiant　temperatures.　Thermal　remote　sensing　data　were　obtained　from　band　6　of　two　Landsat　TM/ETM+　images　of　1989　and　2000　to　observe　the　UHI　changes　over　11-year　period.　The　thermal　infrared　bands　were　processed　through　several　image　enhancement　technologies.　This　generated　two　3-dimension-perspective　images　of　Xiamen＇s　urban　heat　island　in　1989　and　2000,　respectively,　and　revealed　heat　characteristics　and　spatial　distribution　features　of　the　UHI.　To　find　out　the　change　of　the　UHI　between　1989　and　2000,　the　two　thermal　images　were　first　normalized　and　scaled　to　seven　grades　to　reduce　seasonal　difference　and　then　overlaid　to　produce　a　difference　image　by　subtracting　corresponding　pixels.　The　difference　image　showed　an　evident　development　of　the　urban　heat　island　in　the　I　I　years.　This　change　was　due　largely　to　the　urban　expansion　with　a　consequent　alteration　in　the　ratio　of　sensible　heat　flux　to　latent　heat　flux.　To　quantitatively　compare　UHI,　an　index　called　Urban-Heat-Island　Ratio　Index(URI)　was　created.　It　can　reveal　the　intensity　of　the　UHI　within　the　urban　area.　The　calculation　of　the　index　was　based　on　the　ratio　of　UHI　area　to　urban　area.　The　greater　the　index,　the　more　intense　the　UHI　was.　The　calculation　of　the　index　for　the　Xiamen　City　indicated　that　the　ratio　of　UHI　area　to　urban　area　in　2000　was　less　than　that　in　1989.　High　temperatures　in　several　areas　in　1989　were　reduced　or　just　disappeared,　such　as　those　in　old　downtown　area　and　Gulangyu　Island.　For　the　potential　mitigation　of　the　UHI　in　Xiamen,　a　long-term　heat　island　reduction　strategy　of　planting　shade　trees　and　using　light-colored,　highly　reflective　roof　and　paving　materials　should　be　included　in　the　plans　of　the　city　planers,　environmental　managers　and　other　decision-makers　to　improve　the　overall　urban　environment　in　the　future.