An improved explicit analytical evaluation algorithm of reliability indices is proposed for distribution network planning. Differences between feeder topologies are measured by the tree edit distance

which is used in the hierarchical clustering algorithm for the planning area. By choosing the clustering centers as typical topologies

which take the place of the simple radial topology in the traditional approximate evaluation algorithm

the reliability evaluation model is established. Based on the up-stream isolation and down-stream transfer capability of each typical topology

reliability indices are formulated by regressive analysis

respectively. The influences from various reliability enhancement equipment and different outage modes are included in the process. A city distribution network case study shows that the proposed algorithm can still guarantee a high calculation accuracy when faced with various topologies. Besides

it can improve the solution quality and stability in the distribution network planning optimization process.