提出带负授权和权限层次的扩展RBAC模型并分析模型中由负授权引起的冲突。用OWL-DL表示该扩展模型并说明如何使用OWL-DL推理引擎检测扩展模型中潜在的冲突。 This paper proposes an extended RBAC model with negative authorization and authorization level and analyzes the conflicts caused by negative authorization in the model. OWL-DL is used to represent this extension model and to illustrate how to use the OWL-DL inference engine to detect potential conflicts in extended models.