Due to a rapid increase in the number of functionally equivalent web services at open and dynamic Io T service environment,Qo S has become a major discrimination factor to reflect the user’s expectation and experience of using a service.There are different languages and models for expressing Qo S advertisements and requirements among service providers and consumers.Therefore,it leads to the issues of semantic interoperability of Qo S information and semantic similarity match between a semantic description of the service being requested by the service consumer,and a formal description of the service being offered by the service provider.In this paper,we propose a hierarchical two-layer semantic Qo S ontology to promote the description and declaration of Qo S-based service information in detail for any domain and application.And,we develop a semantic matchmaking algorithm to compare the web services according to their Qo S information and adopt analytical hierarchy process( AHP) to make decision for the ranked services depending on the Qo S criteria.The comparison study and experimental result show that our proposed system is superior to other service ranking approaches. Due to a rapid increase in the number of functionally equivalent web services at open and dynamic Io T service environment, Qo S has become a major discrimination factor to reflect the user’s expectation and experience of using a service. Here are different languages ​​and models for expressing Qo S advertisements and requirements among service providers and consumers.Therefore, it leads to the issues of semantic interoperability of Qo S information and semantic similarity match between a semantic description of the service being requested by the service consumer, and a formal description of the service being offered by the service provider. In this paper, we propose a hierarchical two-layer semantic Qo S ontology to promote the description and declaration of Qo S-based service information in detail for any domain and application. And, we develop a semantic matchmaking algorithm to compare the web services according to their Qo S information and adopt analytical hierarchy process (AHP) to make decision for the ranked services depending on the Qo S criteria.The comparison study and experimental result show that our proposed system is superior to other service ranking approaches.