Distribution system reliability plays an important role in the modern society by supplying electric power for customers．This paper introduces the knowledge of minimum way of reliability assessment and the shortest way of finding the shortest route of maximum exploring by adopting C++ program. For the different connecting ways of main line may cause influence to the reliability indexes of the system, it compares and analyses all reliability indexes to the three different connecting ways. The assessing way considers the effects of elements on the minimum route and elements of non-minimum route on the burden point, and the influence of branch route, isolating switch, loading switch, planning check, the power in storage. It is helpful for engineers to find the problems in allocating system and take the corresponding measures.