This paper begins with the analysis of factors affecting the esta-blishmet of network state equations. On the basis of characteristics of networkclement, a rational formntation order of elements as twigs and links is proved.According to the order, a best tree can be drawn, which is helpful to for-mulate state equations, Two examples are enumerated On the basis of the besttree, topological equations of network are written. By inserting operationswith both topological equations and characteristic formulas, a standard stateequation is derived as a result of eliminating the undesired variables. Thismethod is simpler and more convenient as compared with the others in theand has advantage of both the topological method and the direct operations,method.