In the complex polymorphic system,system reliability is very important,and the most common mode to realize the system reliability is the cold and hot backup mode.In this paper we propose a hybrid redundant backup mode,to calculate the reliability of complex systems and task cost,and to solve the problems of optimization distribution and initialization of backup components in complex system.With the probability distribution of discrete mathematics,this paper mainly calculates the reliability and task cost of components in complex system.Then,use quantum genetic algorithm to solve the problem of redundancy backup element optimization distribution.Finally,simulation is implemented to calculate the reliability of the system,the expected task cost,and optimization distribution of redundant backup devices.It concludes the balance relationship between reliability and task cost of complex system.