Abstract: On the basis of classical elastic-plastic constitutive model framework and double hardening model, we choose two different yield surfaces to establish an elastic-plastic constitutive model of cohesionless sand under vehicle cycle load. The model could reflect cumulative deformation of cohesionless soil with the cycle load. Further, considering the dilatancy phenomenon of sand which occurs under shear condition, the model introduces dilatancy parameter of sand and gives the dilatancy formula of Cambridge model. The research results show that the established model could not only reflect the accumulation plastic deformation of cohesionless sand under the vehicle cyclic load, but also provide the theory basis for developing transportation vehicles or military vehicles with strong passing ability on sand road.