From a global perspective, karst geological disaster has great influence on the tunnel construction. Once it is not handled properly, the karst problems in the tunnel area will cause great disaster, such as water inrush, mud gushing and collapse, etc. These karst disasters seriously affect the construction progress of the tunnel, resulting in equipment damage, casualties, and so on. The construction of Yichang–Wanzhou (YW) railway tunnel has created a miracle in the field of Chinese tunneling. The geology of tunnel area is quite complex, the karst disaster is remarkable, and the engineering construction is extremely difficult. In this paper, the karst characteristics, unfavorable geological disasters, and treatment methods of YW railway tunnel were analyzed systematically. The YW railway tunnel and Zhengzhou–Wanzhou (ZW) railway tunnel are both located in the Qinling-Daba (QB) mountainous area, and the regional geological conditions of them are very similar. Therefore, the research in this paper can be extended to the QB mountainous area, thus providing a reference for the construction of ZW railway tunnel. The investigation can also provide reference for the similar engineering.