Abstarct: The purpose of this research is to identify and prioritize the effective factors in creatingthe risk of construction projects. The statistical population includes two categories of government officials and managers at high levels in the field of construction and managers of contracting companies active in construction projects. The sample size is 18 people who were randomly selected. The questionnaire used is researchermade. The analysis of the research was done in two stages. In the first stage, the risks of construction projects have been collected through interviews and research literature. In order to evaluate and screen risks by managers, Delphi technique has been used in two stages. In the next step, the fuzzy Dimextal technique has been used to find the cause and effect relationships of risks. The results of the research indicate that 34 primary risks were extracted from the interview, and 26 construction risks were finalized in the Delphi technique. 14 pure influencing criteria and 12 pure influencing criteria have been identified in Dimextal technique. Incorrect timings in payments have the greatest impact. And the lack of sufficient expertise of design engineers and consultants is the most effective.