Thispaperpresentsanumericalanalysisofgas-solidseparationinarotationaltubeseparator.Thisseparatorwhichcollectsfineparticlesfromgasinlaminarflowiseffectiveforfineparticleseparation.TheseparationefficiencyandcriticalparticlediameteroftheseparatorweresimulatedusingCFDpackage(FLUENT6.0).Thesimulationshowedthatseparationefficiencycanbesignificantlydecreasedduetothepresenceofturbulence.ThesimulationalsoshowedthattheSaffmanliftforcehaslittleeffectontheefficiencyofthisseparator.Thecriticalparticlediameterofthistubeseparatorwasalsocalculatedtheoretically.Someexperimentaldatawereprovidedtovalidatethesimulationresults.Comparisonbetweenexperimentalresultsandsimulationpredictionsonseparationefficiencyshowedsatisfactoryagreement.