Abstract: The reason for the appearance of internal friction in tubular piles is that the relative displacement or its trend exists between the soil core and piles.With linear elastic-plastic load transfer function,on the basis of foregoing work,a set of analytical equations for the axial load-settlement curves of thin-wall cast-in-situ tubular piles were deduced with the internal friction exerting along with the outer friction.Correlative parameters of the pile-soil system could be obtained from the measured load-settlement curves,and the distribution equations of axial force and friction along piles could be calculated.A case study was given to validate the present method.