The　distribution　network　plays　a　great　role　in　the　power　system,　and　any　fault　in　it　may　threaten　the　safe　and　stable　operation　of　the　power　system.　Hence,　fault　diagnosis　has　an　important　role　in　protecting　the　distribution　network　and　maintaining　power　system　stability.　The　model-based　diagnosis　(MBD)　is　one　of　the　diagnostic　methods　that　have　some　advantages　compared　with　the　common　diagnosis　methods.　The　latter,　such　as　expert　diagnosis　systems　depend　on　the　professional　experience　and　fault　information.　However,　the　inefficiency　and　incomplete　calculation　of　the　minimum　hitting　set　(MHS)　limits　the　performance　of　the　MBD.　In　this　paper,　to　overcome　these　limitations,　an　innovative　MHS　algorithm　which　considers　the　nature　and　characteristics　of　the　distribution　network　is　proposed.　In　the　proposed　algorithm,　a　new　fitness　function　is　constructed　by　a　weighted　combination　method,　which　allows　particles　to　move　directly　toward　the　MHS　without　the　effect　of　non-hitting　set　particles.　Finally,　three　cases　studies　and　discussion　on　the　distribution　network　are　introduced　to　validate　the　advantages　of　the　proposed　algorithm,　in　terms　of　the　computation　efficiency　and　accuracy.