Abstract: Whenspacecraftworks,itwillsufferdifferenttemperatureenvironments,whiletemperaturedifferencewillalwaysintroducechangesofshapeandsizeofcompositestructures.However,somespacecraftpartsneedhighdimensionalstabilitytokeepitsrightfunction.Tillnow,themechanicalpropertiesofthecompositehavebeenwidelystudied,however,thethermalpropertiesofcompositeandoptimizationofcompositeconsideringboththermalandmechanicalpropertiesarefarfromwellstudied.Compositetubeswereoptimizedtoagivencoefficientofthermalexpansion（CTE）,andthestiffnessofthosetubeswastakenintoconsiderationatthesametime.Firstly,multiscalenumericalmodelsweredevelopedtocalculatetheCTE.Inmicro-scalemode,theCTEofunidirectionalfiberreinforcedcompositewascalculatedbythefiberCTEthroughrepresentativevolumeelements（RVE）.In macro-scale,acompositetubemodelwasgeneratedtopredictbothaxialandtransverseCTEofthetubebasedontheCTEcomputedbyRVE.Compositelaminatesandtubeswithgivenplieswereanalyzedandtested.Comparisonbetweenthepredictedresultsandtheexperimentaloneverifiedthemodel,whichmadethefoundationfortheoptimizationmode.Secondly,optimizationmodelsforcompositetrussstructurewerecreated.Theconjugategradientmethodwasadoptedtooptimizethepliesofcompositeparts,andthethermal-mechanicaloptimizingmethodwasdeveloped.Finally,thesatellitesupporttrussstructurewasanalyzedbythethermal-mechanicaloptimizingmethod.Analyzedresultsshowthatthisoptimizedsupportstructureandthewholeantennahaveanexcellentthermaldimensionalstability.Thethermalmechanicaloptimizingmethodcanbeusedforthermalstabilitydesignandanalysisofcompositesupporttrussstructures.

Key words: Truss, Multi-scale；Optimizingdesign, Thermalstability, Representativevolumeelement, Coefficientofthermalexpansion, Satellite