Historical　seismic　events　show　that　water　supply　networks　are　increasingly　vulnerable　to　seismic　damage,　especially　in　a　violent　earthquake,　which　leads　to　an　unprecedented　level　of　risk.　Evaluation　of　vulnerability　to　seismic　hazards　can　be　considered　as　one　of　the　first　steps　of　risk　management　and　mitigation.　This　paper　presents　a　stochastic　interpolation-based　fractal　model　for　assessing　the　physical　vulnerability　of　urban　water　supply　pipelines.　Firstly,　based　on　the　formation　mechanism　of　natural　disaster　risk　and　the　concept　of　seismic　vulnerability,　the　most　representative　factors　were　selected　as　the　vulnerability　evaluation　indices,　and　the　classification　criterion　of　each　index　was　teased　out　according　to　the　earthquake　damage　investigations　and　researches　on　the　aseismatic　behavior　of　water　supply　pipelines.　Secondly,　considering　the　randomness　of　vulnerability　to　earthquake　hazards,　the　test　data　set　was　produced　by　way　of　stochastic　interpolation　according　to　the　uniform　distribution,　on　the　basis　of　the　classification　criterion.　The　fractal　dimensions　of　all　of　the　indices　were　calculated　based　on　the　test　data　set.　The　fractal　interpolation　diagnosis　function　for　identifying　the　vulnerability　levels　of　pipelines　to　earthquake　disasters　was　established.　Finally,　the　application　of　the　proposed　model　to　a　real　water　supply　network　and　its　comparative　analysis　showed　that　the　water　supply　network　was　basically　in　a　medium　vulnerability　level.　Through　the　case　study　verification,　we　could　find　that　the　model　was　theoretically　and　practically　feasible.　This　study　helps　to　gain　a　better　understanding　of　the　extents　of　potential　vulnerability　levels　of　water　supply　pipelines.　It　can　provide　technical　support　for　disaster　prevention　plans　of　urban　water　supply　networks.