Green spaces are essential urban infrastructure and central venues for residents' activities,exerting a substantial impact on residents' mental health. Current research predominantly assesses the impact of green spaces on residents' mental health from a static environmental standpoint,overlooking the behaviors and perceptions of individuals within these spaces. Moreover,the relevant influencing factors are based on quantitative indexes to measure the availability of green space,ignoring its quality differences. Using survey data from 712 questionnaires across 24 communities in Tianjin,this study classifies greenspace exposure into categories of passing-through and staying-within,developing corresponding measurement methods to accurately characterize the exposure. Furthermore,the study employs a multilevel linear regression model and mediation analysis to investigate the effects of residents' greenspace exposure on mental health,uncovering the roles of residents' social interactions and physical health as mediators. In particular,this study emphasizes the differences in results from a dynamic individual-environment interaction perspective compared to a traditional static environmental perspective. Additionally,landscape indicators assessing spatial quality are incorporated to establish a holistic system of influencing factors. The final results indicate that: (1) Residents' behavior in using green space is related to the supply of green space around the community. Residents' green space activities are characterized by high frequency and brief stay time in communities with abundant green space. (2) Compared with the environmental factors,such as greening rate and green looking ratio,the individual-environment interaction factors,such as greenspace exposure,have a more significant impact on residents' mental health and provide stronger explanatory power. This indicates that the health-promoting effects of the environment depend on individuals' actual exposure behaviors. (3) The quality of green space landscapes will affect the extent of residents' participation in these areas and is significantly correlated with their mental health. (4) To a certain extent,greenspace exposure and greenspace contact influence residents' physical health and social interaction,which in turn further affect their mental health. Specifically,residents' physical health serves as a mediator in the relationship between passing-through and staying-within greenspace exposure and mental health. Residents' social interaction levels partially mediate the relationship between staying-within greenspace exposure and the landscape fragmentation patterns. This research provides an innovative quantitative method to measure individuals' actual exposure levels to green spaces,advancing the assessment of positive environmental exposure methods. Additionally,the study clarifies the relationship between individuals and environment,improves the "people-oriented" influencing factor system,and provides valuable insights for health-oriented ecological environment improvements and sustainable urban planning.