The invention discloses a service combining and replacing method based on a service cluster. The service cluster is constructed with an existing service clustering method, and a formal description method of services and the service cluster is put forward based on a Petri network; and the input and output parameters of the services are represented in an abstract way, and the input and output parameters of the services are described through a parameter matrix. Through adoption of a service matching method in the invention, universality and individuality can be fully realized among the services in the service cluster, and the service discovery and combining efficiencies are increased by narrowing of a service discovery range. A Web service combining and replacing method is provided through improvements on a service cluster model. Parallel combination and serial combination of the services in the service cluster are described respectively, and rapid service combination is realized in the service cluster, so that efficient service combination and replacement are realized. Through adoption of the service replacing method in the invention, single service replacement in the service cluster can be realized, and service combination and replacement in the service cluster can be realized.