Cloud computing, a common business model, provides cloud resources on demand to consumers over the Internet. However, because cloud computing lacks a uniform method of representing knowledge, which can offer customers a comprehensive solution for managing and developing cloud applications, cloud computing has low reuse potential. This work proposes a Semantic Agent as a Service (SAaaS), which was developed using Unified Modeling Language modelling. The SAaaS architecture is based on research into Cloud Computing, Semantic Web and Multi-Agent Systems. The architecture can be combined with existing cloud service models, such as Software as a Service, Platform as a Service and Infrastructure as a Service, to design intelligent cloud computing applications. To demonstrate the efficacy of SAaaS, a Semantic-based Project Resources Sharing Platform, an intelligent cloud computing application based on the SAaaS framework, is implemented to provide project resources on demand, consistent with the needs of project members.