Abstract: The tunnel sections through the large fault (fracture) zone are often considered as hidden danger sections for the construction and operation of tunnel engineering, so it has always been the focus and hot spot in survey, design and construction research. Taking the main line diversion tunnel (No.2 tunnel) passing through the Zhushan fault of the water resource allocation project under construction in the central urban area of Shiyan City as an example, the geological defects of the Zhushan fault are analyzed according to the engineering geological conditions of the research area and the spatial distribution and geological characteristics of the Zhushan fault. The results show that the Zhushan fault has three major geological defects, the complex material composition of the fault zone, the weak and broken lithology of the fault zone, and the rich water content in the fracture zone. The engineering response strategy for the main line headrace tunnel crossing the Zhushan fault is furtherly analyzed and studied by drawing on the engineering construction experiences of completed tunnel in this project. The specific technical route of the engineering response strategy is summarized as follows: applying concept of refinement engineering technology to formulate an economical and reasonable and technically feasible tunnel excavation and support plan; utilizing comprehensive survey methods to carry out refined and advanced geological forecasting work; refining the construction treatment measures and adjusting the tunnel excavation support plan in time; carrying out tunnel construction according to the determined tunnel excavation and support plan; strengthening the deformation monitoring of the tunnel and adapting design scheme in time to the revealed geological conditions.