Abstract: To deal with the engineering complexity during the process of developing complex distributed systems,a software modeling approach for the Intelligent-agent oriented system has been proposed.The extended UML diagram and the sequence diagram are used to identify potential intelligent agents,and an agent class model is generated by specifying its mental state characters.The agent dynamic action model is developed with extended UML state diagram and Petri net graph.An example of developing a telecom network resource management system has been illustrated,which indicates that the modeling approach provides efficient solutions to manage the domain complexity.