In the recent years, the importance of supporting dynamic configuration in distributed systems has been widely recognized by many researchers. A new model ExGOM(extended graph-oriented model) supporting dynamic configuration by improving and extending GOM (graph-oriented model) is proposed in this paper. ExGOM supplies abundant configuration functions based on graph constructs. The user can define dynamic changes of the system architecture in the configuration file, or by using the configuration functions in the programs. This is a significant attribute so that the model can support unpredicted(non pre-planned) dynamic configuration. Also in this paper, the system architecture of the model implemented by a multi-agent mechanism is presented.