Theelectrostaticsheathwithacylindricalgeometryinanion-electronplasmaisinvestigated.AssumingaBoltzmannresponsetoelectronsandcoldionswithbulkflow,itisshownthattheradiusofthecylindricalgeometrydonotaffectthesheathpotentialsignificantly.Wealsofoundthatthesheathpotentialprofileissteeperinthecylindricalsheathcomparedtotheslabsheath.Thedistinctfeatureofthecylindricalsheathisthattheiondensitydistributionisnotmonotonous.Thesheathregioncanbepidedintothreeregions,twoascendantregionsandonedescendantregion.