Abstract: This paper will take a tunnel project as an example, focus on the safety issue of underground tunnel under extreme weather conditions and explore the evolution characteristics of surrounding rock stress field and the influence law of rainfall and water accumulation on tunnel safety under the condition of different water contents and different water accumulation depths on the surface of the tunnel. The numerical calculation model of tunnel under extreme weather conditions was established by using FlAC^3D finite element simulation software. The results show that the pressure and tensile stress of the surrounding rock of the subway tunnel increase sequentially with the growth of the moisture content of the overlying stratum, but it is not large enough to cause tunnel damage. In addition, the surrounding rock stress increases with the depth of water, when it reaches 2 m, the maximum compressive stress raises by 7%, which may have some impact on the safety or water seepage of the weak link of the tunnel. Aiming at the shortcomings of traditional analytic hierarchy process and entropy weight theory on determining the weight of index, a tunnel safety prediction method based on game theory is established. The prediction result is basically reliable.