Tunnel construction is one of the most complex construction projects and risks are an inseparable part of such projects. Achieving the goals of any construction project with the least deviation requires the correct identification of its risks, which mostly have negative effects on the project's goals. Furthermore Identification and prioritization of risks is one of the most important steps in risk management. Therefore, the main goal of the current research is to identify and rank the risks of tunnel construction in construction projects. This research was applied in terms of purpose and descriptive-survey in terms of method. The statistical population of the current research is experts in the field of tunnel construction (including managers, specialists, engineers, consultants, etc.) assuming the conditions that 12 of them are in the CVR department and 15 of them are in the FCM department were chosen as a sample. To analyze the data, Content Validity Ratio (CVR) and Fuzzy Cognitive Map (FCM) technique were used to identify and determine the structure of relationships between risks and determine the degree of effectiveness (Outdegree and Indegree). The results of study showed that seven factors and 48 risks including Investment, financial and legal factors with 7 risks; Technical management with 11 risks, Human factor with 6 risks, Safety management with 8 risks, Geological discoveries with 6 risks, Material factor with 5 risks and Managerial and political factors with 5 risks in the construction and construction of metro tunnels. The Investment, financial and legal factor with a 3.69 outdegree has the most impressive among the factors on the construction of the Mashhad-Golbahar tunnel project. Also the results of the risks of this factor showed that; The risks of specific project financing methods with an impact coefficient of 3.92 have the highest impact among the risks of this factor.