According　to　the　structure　feature　of　weakly　meshed　network　in　high　voltage　distribution　systems,　a　new　algorithm　of　reliability　evaluation　is　proposed　based　on　the　theory　of　minimum-cut　set.　The　active　failure　of　components　is　simulated　by　seeking　node　group　components,　and　flow　algorithm　for　weakly　meshed　network　based　on　compensation　method　is　adopted.　The　capacity　constraints　of　components　are　considered,　and　meanwhile　the　effects　of　component　plan　maintenance　and　back-up　power　are　taken　into　consideration.　The　reliability　evaluation　for　the　RBTS-BUS4　system　and　a　practical　distribution　system　are　conducted.　The　system　and　nodal　reliability　indices　are　calculated　and　weak　links　are　identified,　which　will　help　to　provide　guidance　for　the　upgrading　of　power　grids.