A service substitution method is proposed based on service clusters.The services in a service library are clustered and service clusters are formed.The net unit and matrix models of a service cluster are constructed.Assume that the service composition based on service clusters is established

the model of the combination service net is established by analyzing the combination processes.From the standard matrix model of a failure service and the model of the combination service net

a quick finding and substitution algorithm of services is presented.The correctness and validity of the proposed method are illustrated by an example.Also

the experiment results show that the efficiency of service substitution can be enhanced and the rubusteness of service composition can be kept based on the standard matrix model of the failure service.