Abstract: While service individual’s QoS description is from its own viewpoint,there is a semantic gap between these services’ description．Based on a hierarchical ontology model,a QoS ontology model was proposed,which establishes the relationship between user QoS and service QoS．And the QoS aggregation mechanism was studied for several basic structures．A QoS aggregation algorithm was proposed to aggregate the QoS of whole composite service．Further,A QoS translation algorithm was discussed to translate service QoSs to user QoSs,and it satisfies the end-to-end QoS requirements.

Key words: QoS,End-to-end user requirement,Service composition,QoS aggregation