For resources in an open environment, the access control rules (ACRs), which are described by extensible access control markup language (XACML), might have conflicts between each other. To improve the rule management, the root causes of rule conflicts must be identified. This paper firstly formally models the resource attributes by dynamic description logic (DDL), and then investigates inference problems like attribute consistency and rule satisfiability by setting up concept, instance and action knowledge bases. Next, DDL-based rule conflict detection algorithms were designed to identify possible rule conflicts. Finally, the feasibility and decidability of the proposed algorithms were verified through experiments on expanded Continue dataset. The research results provide new insights to the detection of conflicts between resource authorization rules (RARs).