The　effect　of　the　atomic　oxygen　(AO)　and　ultraviolet　(UV)　irradiation　on　the　microstructures　and　properties　of　Kapton/Al　second　surface　mirror,　a　thermal　control　coating　for　keeping　equilibrium　temperature　of　the　spacecraft　exterior　surf　aces　in　low　earth　orbit　(LEO)　environment　was　investigated　by　ground　simulationtest　test.　The　irradiated　surfaces　of　Kapton/Al　coatings　were　characterized　with　high　precisi　on　micro-balance,　scanning　electron　microscopy,　UV/Vis/NIR　spectrophotometer　and　X-ray　photoelectron　spectroscopy.　The　results　show　that　the　AO　and　UV　irradiation　has　a　major　impact　on　the　surface　roughness　and　reflectance　of　the　Kapton/Al　coatings.　For　instance,　as　the　irradiation　time　increased,　the　mass　loss　and　surface　roughness　linearly　increased　and　the　reflectance　decreased,　accompanied　by　an　increased　solar　absorptance;　when　it　comes　to　surface　damages,　the　combined　AO　and　UV　irradiation　outperforms　the　AO　irradiation.　In　addition,　the　complicat　ed　contents　observed　on　the　surfaces　indicate　a　series　of　the　irradiation-induc　ed　chemical　reactions.　©,　2015,　Zhenkong　Kexue　yu　Jishu　Xuebao/Journal　of　Vacuum　Science　and　Technology.　All　right　reserved.