Traditional model of distribution networks mostly research the response of input excitation, by describing elements and connections of elements for distribution networks. When the states of vertexes in distribution networks have changed, the connections of elements transformation. Owning to the mutual couplings and branches of distribution networks, it is hard to achieve the global optimization for load balancing, reconfiguration and restoration after fault by nomograph. A new model based on hierarchical model is presented. This model can be employed to identify the zone and branches efficiently and offer a cogent topological analysis method for the global optimization. The test result shows the effectiveness of the proposed method.