Appropriate environmental performance is considered one of the most important indicators in the sustainable development of organizations and industries. Evaluating the environmental performance in ports as one of the two main parts of the maritime transport system is of particular importance. Therefore, the current study was designed and conducted to develop a method for evaluating the environmental performance of ports based on the Fuzzy Analytic Hierarchy process (FAHP). In the present study, 22 experts in the field of environment and marine sciences were selected in 2020. Firstly, various studies on the factors affecting the environmental performance of ports were reviewed. Secondly, a questionnaire was designed to assess ports’,environmental performance. Thirdly, this questionnaire was developed using the Delphi technique. Finally, by determining the weight of each parameter, the method of environmental performance assessment in ports was developed based on the FAHP. The final normalized weights for six environmental performance factors including reactive and proactive performance, sustainability, socio-cultural, economic, and governance were estimated 0. 202, 0. 241, 0. 226, 0. 070, 0. 080, and 0. 182. Additionally, it was found that each of the parameters had a different weight and impact on these factors. The highest and lowest impact on the environmental performance index belonged to environmental risk assessment (weight=0. 217), cultural effects, and justice (weight=0. 107). In the current study, a new method was developed for evaluating the environmental performance of ports based on six factors, 32 parameters, and FAHP. Therefore, this method may provide an effective step in reducing environmental impacts and improving the level of environmental performance in ports to achieve the goal of green port.