With the acceleration of urbanization around the world, city dwellers face increasing levels of work stress and mental health issues, which negatively impact their happiness. The purpose of this study was to explore the impact of natural environment on residents' mental health and well-being in urban forest parks, and to analyze the relationship between natural environment perception, psychological recovery, restorative environment perception and subjective well-being. Through a questionnaire survey conducted in a botanical garden in Hunan Province, 504 valid samples were collected. Through structural equation model (SEM) analysis, the results show that: (1) natural environment perception has significant positive effects on psychological recovery and restorative environment perception. (2) Psychological recovery as an intermediary variable significantly improved residents' subjective well-being. In addition, the characteristics of an individual's social background, such as gender, education level, occupation, and frequency of visits, are closely related to the perception and well-being of the natural environment. Among them, the increase of the frequency of visit has a significant positive effect on the improvement of individual's natural environment perception, restorative environment perception, subjective well-being and psychological recovery. The results show that: (1) Urban planners should improve the accessibility of urban forest parks and integrate restorative elements into the design. (2) Encourage residents to visit frequently to improve mental health and well-being. The results of this study provide empirical support for the value of urban forest parks in promoting public mental health and well-being, and provide scientific basis for urban planning and green space management.