Abstract: Thedevelopmentofthecomplexmultibodyspacecraftraiseshigherrequirementtomulti-bodydynamicsmodelingandcontroltechnology.Theexplicitdynamicsequationsofthesystemarealwaysneededtoanalyzesystem′scharacteristicsanddesigncontrollers,butthecomplexityofsystembringsdifficultytoderivingtheequations.Inordertosolvethisproblem,theexplicitformofdynamicsequations′analyticalexpressionwasinferredbyusingKane′smethod,thechainstructuresystem′sexplicitdynamicsequations; then,byanalyzingthisequation,physicalmeaningandregularitiesofdistributionofeachequationitemwere  established;usingthoseregularities,aprogramthatcanoutputtheexplicitdynamicsequationsofspacecraftsystemwithtreestructurewasdeveloped.Thisprogramreducestheworkloadofmodelingthistypeofspacecraftsignificantly.

Key words: multi-bodysystem, roboticarm, explicitformationofdynamics, autowriting, Kaneequation