Afrequencyandspatialdomaindecompositionmethod(FSDD)foroperationalmodalanalysis(OMA)ispresentedinthispaper,whichisanextensionofthecomplexmodeindicatorfunction(CMIF)methodforexperimentalmodalanalysis(EMA).ThetheoreticalbackgroundoftheFSDDmethodisclarified.Singularvaluedecompositionisadoptedtoseparatethesignalspacefromthenoisespace.Finally,anenhancedpowerspectrumdensity(PSD)isproposedtoobtainmoreaccuratemodalparametersbycurvefittinginthefrequencydomain.Moreover,asimulationcaseandanapplicationcaseareusedtovalidatethismethod.