It is known that the representation and utilization of real-world dynamic knowledge are increasingly important to open and dynamic computing environments, but traditional semantic web ontology and current existing context-aware systems are still unsuitable to process real-world dynamic knowledge. To solve this problem, by virtue of the advantage of Pragmatic Web in dynamic knowledge expressing and processing, a Pragmatic Web oriented Context-Aware System (called PWCAS) is proposed, and its architectural framework is designed, which not only can capture users real intention by inter-agents semantic negotiation and preliminarily can achieve the personalized user-centric services.