Methodology: Therefore, the aim of the present study is to identify and classify the factors affecting the inner-city natural areas on the promotion of the mental health of citizens in selected neighborhoods of Hamedan. This study is applied in terms of its purpose and qualitative in terms of its nature and method. In this regard, the fuzzy Delphi technique was used to identify the dimensions and components that are effective in explaining the inner-city natural environments on the promotion of the mental health of citizens, and then the structural-interpretive approach (ISM) was used to classify and analyze the relationships between the components. The research population included 15 experts in the fields of inner-city natural environments on the mental health of citizens in selected neighborhoods of Hamedan, Koy Pardis and Golan neighborhoods, who were selected using a purposive sampling method and a snowball method.

Results: Analytical findings based on research indicators show that indicators such as air quality, children's access to green space, a sense of belonging to the neighborhood's nature, and citizen participation have the greatest impact on improving citizens' mental health.

Conclusion: The structural-interpretive approach showed that the mental health of citizens is at the first level, the naturalistic city and the social index of naturalism are at the second level, and the economic index of naturalism is at the third level. Cities that follow the naturalistic city model have a higher ability to reduce psychological harm, promote environmental sustainability, and increase general satisfaction indices. The social and cultural dimension of naturalism should be considered along with physical investment, because without active citizen participation and environmental education, the realization of a naturalistic city will not be successful.