Abstract: The evaluation of interlayer fatigue performance of asphalt pavement is highly dependent on fatigue life．But the factors considered in the existing interlayer fatigue life prediction model are not comprehensive enough，and there is no correlation between the interlayer fatigue life prediction model and the initial shear stiffness． In this study，four-point shear fatigue tests under four external factors (i． e． shear stress amplitude，temperature，loading frequency，normal stress) were carried out and Initial Shear Stiffness (ISS) and Shear Stiffness Decay Rate (SSDR) of interlayer performance were obtained． Nonlinear multiple regression models for ISS and SSDR were established，respectively． And an interlayer fatigue life N f prediction model was constructed based on ISS and SSDR． The results show that: (1) the influence degree of four external factors on the interlayers ISS ranks: tem-perature ＞ shear stress amplitude ＞ loading frequency ＞ normal stress; the influence degree of four external factors on the decay rate of interlayer shear stiffness ranks: normal stress ＞ temperature ＞ shear stress amplitude ＞loading frequency; the influence degree of four external factors on interlayer fatigue life ranks: temperature ＞ nor-mal stress ＞ shear stress amplitude ＞ loading frequency; (2) the interlayer fatigue life N f prediction model based on ISS and SSDR realizes the correlation among the three indexes of the interlayer fatigue life N f ，ISS and SSDR． The research results provide a new way for the prediction of interlayer fatigue life and a theoretical support for strengthe-ning interlayer design．

Key words: road engineering, asphalt pavement, interlayer fatigue model, initial shear stiffness, shear stiffness decay rate, multiple regression