At-rest earth pressure codfficient,K0,is very important in geotechnical engineering design and finite element analysis. At present, it’s treated as a constant usually for given soil in FEM analysis. However recent test results indicate that K0 of both clay and sand varies with pressure increasing nonlinearly. It’s shown that Duncan-Chang model, a kind of hypoelastic model widely used, can reproduce K0 varying with pressure. The calculating procedure of K0 derived from Duncan-Chang’s E-B model is proposed, and then influence of model parameters on calculated K0 is explored. Studies show that cohesionless soil’s calculated K0 decreases with pressure increasing, while cohesive soil’s calculated K0 increases with pressure increasing. Three of the seven model parameters, m, Kb and Rf, have a positive correlation with calculated K0, and there is a negative correlation between the residual parameters and calculated K0.The influence of seven model parameters on the calculated K0 decreases gradually in the following order: m ,n, Rf, φ, c, K, Kb.