Abstract: Aspacedebriscloudconsistsofnumerousbreakupfragmentswhichareoriginatedfromaninstinctspaceobject.Asthebreakupfragmentsareinaconcentrateddistribution，thosespacecraftintheneighborhoodofthebreakupobjectswillfaceaseriousthreatofcollision.Inordertoevaluatethelongtermevolutionofspacedebris，thepropagationofspacedebriscloudforashorttermperiodwasanalyzednumerically.Basedonthestabledistributioncharacteristicofthedebriscloud，fragmentsweredividedintoseveralgroupsaccordingtotheirorbitalheightsandareamassratios.Thelongtermdistributionundertheperturbationofatmospheredragwasdescribedbyananalyticevolutionmodel.Comparing〖JP2〗withallthefragmentspropagatingindividually，theanalyticmodelwasmoreefficientandlesstimeconsuming.Theevolutionofabreakupdebriscloudconsists1780breakupfragments，andwasobtairedforthenextfiftyyears.Resultsshowthatthepeakspatialdensityofthedebriscloudisaroundtheheightofthebreakupobjectandwillspreadintoabroaderheightintervalcontinuously,andthefragmentsinthelowerheightintervalwillfirstlyincreaseandthendecreaseundertheperturbationofairdrag.

Key words: spacedebriscloud, spatialdensity, breakupmodel, debrisdistribution, evolutionmodel