Rubber asphalt and SBS modified asphalt were prepared in routine way and stress absorbing layer mixtures were designed with suitable gradations. At the same time, Strata stress absorbing layer was regarded as contrast material. Through a large number of four point bending beam fatigue test(at 15℃) performed on these three asphalt mixtures with strain of 1500×10-6, relationships between fatigue life of the mixtures and crumb rubber content(by mass), SBS modifier content(by mass) and penetration, softening point and viscosity of modified asphalt were investigated. The results show that the Strata stress absorbing layer mixtures fatigue life is 302023, so the fatigue life of greater than 3×106 times under strain of 1500×10-6is taken as a judgment standard of fatigue life. The fatigue life of rubber asphalt stress absorbing layer mixture has a relatively good correlation with crumb rubber content and viscosity of rubber asphalt at 177℃, crumb rubber content is required ranging at 19.6%20.5%, 177℃ viscosity is required to be 3.43.6Pa·s. Fatigue life of SBS modified asphalt stress absorbing layer mixture has a good linear correlation with SBS modifier content and penetration, softening point, 135℃ viscosity of SBS modified asphalt. If SBS modifier type A and B are mixed together, SBS modifier content≥6.5%, penetration≤5.1mm, softening point≥93℃, 135℃ viscosity≥1.95Pa·s are required. It is also found that fatigue life can be increased by increasing the oil aggregate ratio and adjusting key sieve passing rate in the gradation appropriately, and that type B SBS modifier is more suitable for stress absorbing layer mixture design.