Abstract: Dynamic description logic (DDL) is an extension of description logic (DL) with a dynamic dimension. In addition to the reasoning mechanism on static knowledge about application domains, DDL also provides a mechanism for representing and reasoning about actions by embracing knowledge of actions into DL. Therefore, DDL is a promising candidate for logic foundations of semantic Web service when every Web service is regarded as an action on Web. Due to such merits provided by DDL, the authors present a DDL-based approach for the description and matching of semantic Web services: Both the goal service of a service consumer and the atomic services from service provider are described in terms of actions of DDL. Then the matchmaker matches the goal service with supplied services by reasoning on actions. The match problem between goal service and supplied services is reduced to the satisfiability problem of formulas in DDL. Compared with the semantic Web service match method based on DL, the DDL based method describes both static information and actions on Web in a uniformal way and the reasoning problem on actions can be reduced to the satisfiability problem of formulas. Compared with the first-order predicate logic, which is often used in action reasoning in situation calculus, the satisfiability problem of formulas in DDL is decidable.