In order to achieve advanced application of a distributed network management system, a kind of node model is proposed based on the comprehensive analysis of the electrical character and operation method of distribution network equipments and the differences of every equipment's application. According to this node model and internal structure of complicated equipments, a new method of topology analyzing complicated equipments is obtained. And then an example to explain how to use this method is given. It is proved by practice that this method not only completes some functions of topology analysis but also achieves power lines topologic coloring.