At present the tunnel bolt-shotcrete support design is still using the engineering analogy method based on the practice experience, and the supporting parameters and surrounding rock geological conditions cannot be completely matched which caused the supporting damage and large deformation in soft and weak tunnels. Taking You Fang-ping Tunnel as an example, analyzed the destruction characteristics and development process of bolting and shotcrete lining through the field investigation. Using Shear-slippage theory, the stability of shotcrete support has been calculated, the result showed that the designed bolt-shotcrete support parameters had enough secure reserve. The construction disturbance caused the weak rock mass into further deterioration which was resulting in shotcrete support system can not meet the design support resistance. The actual deformation larger than design value caused great rock pressure and the formation of shear failure ultimately. It can propose the suggestion for tunnel construction, and provide a reference for disaster prevention and mitigation under similar conditions.