The requirements of service discovery are spread everywhere as service discovery is the prerequisite of resource sharing, data integration and process collaboration in the network environments. In this paper, a unified service discovery framework Service CatalogNet is presented to cover many application scenarios including grid environment. We introduce the service description model in Service CatalogNet which can describe non-functional features by dynamic contexts and is supported by the semantic query engine. We also propose the unified service discovery mechanism and give the evaluations of the algorithm in terms of number of messages and query time.