Abstract An open distributed control system (DCS), which consists of many devices and an open network interconnecting them, is now used in many automation areas. For assuring the control performance under the heavy traffic on the network, the simulation of a DCS is strongly needed. For this purpose, we propose an object-oriented design pattern approach as a uniform, efficient and accurate method of modeling and simulating a DCS. Four design patterns are newly proposed. Device-Constructor and Composite-Device-Constructor patterns describe classes and mechanisms for uniformly structuring device models composed of many kinds of sensors and actuators. Statechart pattern defines classes and the state-transition execution mechanism for realizing the behavior of sensors and actuators in a device. While Event-Chain pattern defines classes and the event dispatching mechanism among sensors and actuators intra-device and inter-device. The systematic implementation procedures from these patterns to the executable Java code of the DCS simulation model are also discussed. Finally, the effectiveness of our approach was proved by developing the Java-based DCS modeler and simulator used in building automation area.