This　paper　presents　the　experimental　measurement　and　numerical　analysis　of　the　current-voltage　characteristics　of　dc　corona　discharges　in　air　between　coaxial　cylinders.　The　current-voltage　characteristics　for　both　positive　and　negative　corona　discharges　were　measured　within　a　specially　designed　corona　cage.　Then　the　measured　results　were　fitted　by　different　empirical　formulae　and　analyzed　by　the　fluid　model.　The　current-voltage　characteristics　between　coaxial　cylinders　can　be　expressed　as　I-=-C(U-U0)m,　where　m　is　within　the　range　1.5-2.0,　which　is　similar　to　the　point-plane　electrode　system.　The　ionization　region　has　no　significant　effect　on　the　current-voltage　characteristic　under　a　low　corona　current,　while　it　will　affect　the　distribution　for　the　negative　corona　under　a　high　corona　current.　The　surface　onset　fields　and　ion　mobilities　were　emphatically　discussed.　©　2015　AIP　Publishing　LLC.