Given the nature of the construction projects, there is a clear presence of diverse stakeholders in such projects. The lack of planning and management of stakeholders in construction projects results in failure to achieve project goals and failures in projects. Therefore, management of stakeholders in construction projects as one of the areas of project management is inevitable. The performance of different stakeholders can impose indirect costs on the project, which can be prevented from imposing overhead on the project, if carefully planned to meet the needs of the stakeholders. In the present research, the goal is to identify and evaluate key stakeholders of the project using the COQ method based on the amount of potential costs that can be imposed on the project. In this method, the costs of the stakeholder performance in the three groups of prevention costs, evaluation costs and failure costs in the construction projects by designing different questionnaires and using a trapezoidal fuzzy method to quantify the questionnaire information are identified and stakeholders are prioritized according to the amount of costs imposed on the project.
