Based on the measured surrounding rock stress, deformation and support structure stress in the weath- ered rock formation, combined with analytical formula calculation and numerical simulation, from the aspects of surrounding rock loose circle radius, support structure deformation and force, this paper evaluated surrounding rock stability and support effect. The results showed that the surrounding rock conditions of the exit section of the Yuliao tunnel were better, the maximum deformation was 7.71 mm, and the thickness of the loose roof of the arch was 3.1 m. The thickness of the loose circle at the arch waist and the arch shoulder was more than 4.0 m. The analysis reflects that the bolts in the loose area of the surrounding rock are subjected to large forces. The stress characteristics of the supporting structure indicate that the additional load transmitted to the supporting structure due to the large deformation of the surrounding rock at the vault and the arch causes the force in- crease. The numerical calculation results show that there is a significant difference in the deformation of the bolts installed in different processes. Based on the deformation law and the force analysis results of supporting structure, the construction measures and support structure optimization suggestions are proposed.