Traditional　GIS　(Geographic　Information　System)　software　development　mode　exposes　many　defects　that　will　largely　slow　down　the　city　informational　progress.　It　is　urgent　need　to　build　a　common　application　infrastructure　for　informational　project　to　speed　up　the　development　pace　of　digital　city.　The　advent　of　service-oriented　architecture　(SOA)　has　motivated　the　adoption　of　GIS　functionality　portals　that　can　be　executed　in　distributed　computing　environment.　According　to　the　SOA　principle,　we　bring　forward　and　design　a　digital　city　geographic　information　common　services　platform　which　provides　application　development　service　interfaces　for　field　users　that　can　be　further　extended　relevant　business　application.　In　the　end,　a　public-oriented　Web　GIS　is　developed　based　on　the　platform　for　helping　public　users　to　query　geographic　information　in　their　daily　life.　It　indicates　that　our　platform　have　the　capacity　that　can　be　integrated　by　other　applications　conveniently.　©　2008　SPIE.