Abstarct: In this study, the risks and their main causes in the tunnel project were accurately identified and evaluated. To further refine the reviews and evaluations in this thesis, we have pointed out the Fuzzy Fault Tree Analysis (FFTA) method and the Fuzzy Analytic Hierarchy Process (FAHP) method to identify the risk parameters and their graphical representation. Because of uncertainty in linguistic words, this thesis uses fuzzy data to analyze quantitative probabilities and the occurrence of risk factors on geological, design, management, safety and cost criteria. It should also be noted that the importance of each criterion was determined by the fuzzy hierarchical process and, by means of this process, the severity of the outcome was combined and the severity of the risk effect was calculated. To this end, firstly in the Tunnel Line Project of Mashhad Metro Line 3, 18 main risks were identified through past studies and interviews with experts and experts in the tunnel construction project. For each of the risks presented, we draw an fault tree separately and use it to evaluate the root cause of the risks. baxsed on this, for quantitative analysis and data collection in the project after the drawing of the error tree, a questionnaire was prepared which was completed by experts and project managers. The analysis of this thesis shows that the risk for cutter-related malfunction, mucking and TBM advance problems, the wear of cutters, the deviation of the path and the clogging and disk obstruction in Mashhad Metro Line 3 Project, factors Have a high risk.