Aiming　at　the　failure　mechanism　of　urban　water　supply　pipeline　in　earthquake,　firstly,　the　main　factors　to　earthquake　damage　and　destruction　of　water　pipes　feature　are　analysed.　Then,　the　fundamental　and　counting　process　of　the　progressive　important　sampling　method　are　introduced.　Finally,　according　to　the　current　code　for　seismic　design　of　pipeline　calculation　model　this　paper　adopts　the　progressive　important　sampling　method　for　structural　reliability　analysis　and　considers　the　stochastic　behavior　of　Pipeline　resistance,　site　condition　and　Pipe-soil　interaction.　By　the　above　description,　calculation　seismic　reliability　assessment　of　urban　water　supply　pipeline　progressive　importance　sampling　method　is　obtained.　The　results　have　indicated　that　the　model　is　objective　and　effective.　©　2015　ejge.