Abstract: Based on reliability theory, using the JC method and the end-off JC method, different factors which affects underground pipelines' reliability index are analyzed. Moreover the effect of large ground displacement caused by earthquake liquefaction on underground pipeline is also analyzed, its result is almost the same as that of a finite element analysis, which proves the result's correctness. At the same time, it offers a reference to underground pipeline's burying which gets through a liquefaction zone.