Modeling and connectivity analysis of network topology are essential in many advanced applications of electric network. In this paper, a modeling and connectivity analysis method for electricity distribution network based on relation database in graphic information system (GIS) is proposed. In the method, an attribute called 'put-cut state' is added to branch, switch is only attached to one branch (line) instead of being taken as a branch, whose state will influence the put-cut state of the branch, all topology information stored in several tables in relation database when the graph of electricity distribution network is being drawn. By such modeling, the connectivity analysis scale of network is reduced and the storage of network topology has the advantage of using some database developing tools to make efficient program. Furthermore, a search method for connectivity analysis is presented and demonstrated by an example.