On the basis of analyzing the occurring mechanism of pile skin friction, pile-soil relative displacement difference function is introduced, and the differential equation which depicts the relationship between pile skin friction and depth is derived, then the calculating model of pile skin friction with depth is established under considering the displacement-interaction process. Field monitoring data are employed to verify the rationality and validity of the model proposed. Through the established model, influences, exerted by pile-soil relative displacement difference, on the pile skin friction distribution are discussed and divided into three stages: I. stage of linear increase; II. stage of nonlinear increase; III. stage of convergence. Filed testing data comparing and theoretical analysis results indicate that the method proposed can describe the transferring process as well as the distribution law of pile skin friction under taking the pile-soil interaction into account, the parameters related and needed can be easily obtained, and the model suggested in this paper is of value in pile theory and engineering.