Access control is an important issue among the security problems of resources in distributed systems. In order to enable entities in distributed systems to understand and interpret policies correctly, common concern is drawn to the problem of expressing access control policies with semantic information. In this paper, we introduce how to express access control policies based on OWL and SWRL. It includes a definition of OWL ontology to describe the terms and a declaration of SWRL rules to explicit the relationship between properties. Finally some use cases are given to explain how to express policies in form of rule using the terms defined beforehand.