Aiming to the distribution network service restoration, this paper proposes a fast topology analysis and power flow calculation method. Firstly, the distribution network structure is stored by SQL relational database. The data maintenance can be convenient and the topology reconstruction can be highly flexible. Both of the node list and branch list store the data loaded from a relational database, which forms the object-oriented real-time database. Then the topology based on the breadth first search method is analyzed, and the power flow combined with the forward and backward substitution method is calculated. Finally, based on C++ programme on QT, the results of topology analysis and power flow on GUI are provided. Results show that the algorithm can quickly detect the distribution network connectivity, judge whether there are loops or isolations, and calculate fast on the premise of the convenient data maintenance.