In　order　to　better　evaluate　the　state　of　sand　liquefaction,　a　kind　of　sand　liquefaction　discrimination　method　based　on　importance　sampling　theory　is　put　forward.　Firstly,　the　earthquake　effect　and　mechanism　of　sand　liquefaction　are　analyzed.　Secondly,　reliability　calculation　performance　function　of　sand　liquefaction　discrimination　is　established　according　to　code　for　seismic　design　of　buildings　(GB50011-2010),　then　the　fundamental　and　calculation　steps　of　sand　liquefaction　reliability　calculation　by　Monte　Carlo　importance　sampling　method　are　given.　Finally,　adopting　this　method　to　make　sand　liquefaction　discrimination　of　Zhang　Zhou　drilling　sites　and　getting　the　sand　liquefaction　reliability　index　and　failure　probability.　It　is　shown　that　the　discrimination　results　are　consistent　with　practical　measured　results,　sand　liquefaction　reliability　index　and　failure　probability　can　describe　sand　liquefaction　trend　quantitatively.　©　2015　ejge.