The method of calculating the frost force of tunnels in frozen soil by analysis on the coupled problem of stress field, thermal field and seepage field is very complicated. In view of this, a semitheoretical and semiexperiential calculation method for the frost force of tunnels in frozen soil is proposed on basis of elasticplastic mechanics and finite element theory. This calculation method is a numerical analysis method for the coupled problem of the dead weight stress field and the thermal stress field based on the determination of the scope of the frozen surrounding rock mass by testing the ground temperature and determination of the physical and mechanical parameters of the frozen and nonfrozen surrounding rock mass by insitu mechanical testing. The calculation method has been verified feasible by mode tests.