Based on the construction project of the Changjiashan tunnel of the freeway,the variety rule of surrounding rock masses of the tunnel through the gob of coalmine was studied by using of finite element methed(FEM). The status of the stress and strain, the variety of the plastic area were simulated in the whole rock mass before and after the tunnel was excavated. The characters of stress and deformation of surrounding rock masses were analyzed when the tunnel was built. It concluded from the numerical simulation that the influence on the tunneling is great when the tunnel passing through the gob of coalmine is excavated, and the relative measures should be taken.