Abstract: Under traffic load, the magnitude of deviatoric stress of subgrade soil varies periodically, and the principal stress axis rotates continually. In order to study the drained deformation behaviors characteristics of subgrade soil due to traffic load-induced stress path, a series of apple-shaped dynamic cyclic stress path tests and conventional dynamic stress path tests are conducted on K₀-consolidated saturated sand using the dynamic hollow cylinder apparatus. Comparisons between the results under the two different stress paths indicate that the continuous rotation of the principal stress axis will accelerate the accumulation of the vertical permanent strains and aggravate the degradation of the resilient modulus. And with the increasing of CSR, the discrepancies in the deformation behaviors under different stress paths become more apparent. Finally, a modified formula for the resilient modulus is proposed to evaluate the principal stress rotation effects based on the Uzan model.