The tunnel excavation is often existed in civil engineering, in which the minimum roof thickness of tunnel is an important index in tunnel construction and design. Some work have been done on this field, by analytical analysis method and numerical simulation method based on linear criterion. In order to add some conclusions to the roof thickness prediction by nonlinear criterions, in the present paper, the calculation model for excavation of tunnel is built by numerical method, the nonlinear criterion is applied to describe the failure situation of the surrounding rock mass; then, according to the reduction method for thickness of roof, the thickness of the roof after excavation in tunnel is analyzed with the nonlinear criterion, to give some guidance for the real practice.