This research was conducted to evaluate and prioritize construction risks in the Caspian Sea coastlines using the fuzzy Dematel approach. The current research was applied in terms of its purpose and descriptive survey in terms of execution. Our statistical community includes experts, supervising engineers, and contractors in the construction field in Tonekabon city. Sampling in this research was done in a non-probabilistic and purposeful way. The criterion for selecting samples in this research was to have at least 5 years of work experience, familiarity with the specialized topics of risks affecting the quality of projects, and the availability of experts, based on which 10 experts were selected. The obtained data were analyzed using the fuzzy DNP method. Each of the risks of pollution, flood, the resistance of the project team with subcontractors to change, changes in the scope of the project, incorrect management style, high humidity, the financial ability of the owner and funding problems, and lack of financial resources of the employer have a positive d + r-value, that is, these risks are effective and can cause other risks in the construction of coastlines. On the other hand, each of the risks of strong coastal winds, insufficient studies and local information about the conditions of the land and the workplace, giving low priority to risk management issues, insufficient commitment to risk management in the construction industry, lack of expert staff, workers' strikes, carelessness of workers, water intrusion In foundation, land collapse, incorrect cost timing are effective due to having a negative D-R value, which means that these risks arise due to non-observance of other risks. The results of the ranking of each risk showed that the risk of geological factors with a weight of 0.184 is in the first place, the risk of management factors is in the second place with a weight of 0.182, the risk of financial factors is in the third place with a weight of 0.180, the risk of technical factors is 0.167 in the fourth place, the risk of human factors with a weight of 0.165 in the fifth place and the risk of environmental factors with a weight of 0.11 in the sixth place.