The fault fracture zone of hydraulic tunnel is always a difficult problem in the process of excavation. In order to ensure the safety of tunnel construction, the construction unit must accurately forecast the geological lithology condition in front of the tunnel by technical means before the tunnel excavation. Based on the Item 172 national key water conservancy project "Four-trunk Canal Extension and water-saving reconstruction Project in Pohu Irrigation District", this paper compares and analyzes the feasibility of predicting the geological conditions of the surrounding rock in front of it, combined with numerical simulation and field test. The results show that the location and scale of the fracture zone can be judged by using the propagation characteristics of electromagnetic wave and seismic wave in the medium filled with clay. Field tests verify the accuracy of GPR and TGP detection technology in predicting the fracture zone of the tunnel. However, the underground geological conditions are complex and changeable, and professional data interpretation personnel are required, and the previous geological exploration data should be combined to make a comprehensive analysis of the poor geological section of the tunnel. The research results provide a good theoretical basis and reference for the advance prediction of tunnel fracture zone, and do a good job in the early stage of tunnel construction to ensure the safety of construction.