Current research has revealed significant benefits of green space exposure (GSE) on psychological stress. However, few studies have explained the cumulative effects of GSE and how these effects vary across different demographic groups, such as gender and education level. This research aims to evaluate the long-term effects of GSE on psychological stress and heart rate variability (HRV) while examining how these effects vary across different demographic groups, such as gender and education level, utilizing Apple Watch data to provide a more objective measure of these effects. In a 6-week experiment, 43 college students were required to engage in GSE at least three times a week, each lasting no less than 10 minutes, based on their schedules. During the experiment, participants wore the Apple Watch continuously to collect physiological data automatically. This study demonstrates a significant reduction in emotional disturbance and notable changes in HRV amplitude following GSE, with variations observed based on gender and education levels. These findings underscore the substantial psychological health benefits of GSE.