Abstract: Thesoilresistanceofpile aroundisoneoftheimportantfactors which affectsthestability ofthe pile ， thustakinginto accounttheinteraction ofpile-soilis morereasonabletostudythe bucking ofthe pile. The horizontal forceofsoilto pileisobtained bythecontinuousconditionsatthesoil-pileandtheorthogonalityoftrigonometricfunctions. Based ontheseresults ， the bendingequation and characteristicequation ofthe pile are established underthree dimensionalaxisymmetricalcases. Theinfluencesofthelength-radiusfactorofpileand modulusfactorofpileandsoilonthe axialcriticalload areinvestigated.