Abstract: The actuality of real-time system development is reviewed and the correlative theories for real-time system schedulability analysis are discussed.One method for real-time system schedulability analysis is presented based on real-time unified modeling language.We have realized the off-line real-time schedulability analysis before system implementation.Through distilling the correlative quantities information of real-time task in the system real-time UML models and analysing by the corresponding tool,the resu...