Abstract: To explore the service capacity of negative air ions and the factors affecting it in Xiamen terrestrial ecosystems, this study took the data of air negative ions generated by the ecosystem that are beneficial to human physical and mental health as the indicator, improved the service evaluation method of negative air ions, based on negative air ion monitoring data, calculated their service function, and analyzed their spatiotemporal dynamic variations and influential factors. The results indicate that the service capacity of negative air ions in Xiamen City was 1.37×10²⁵ ions in 2015, and the service capacity distribution of negative air ions was 0.8×10¹⁶ ions/m². Tong'an contributed the largest proportion of negative air ions of any district within Xiamen City, with a rate of 56.5%. Forestland was the main ecosystem contributor of negative air ions in Xiamen City, with a rate of 86.6%. The daily concentration of negative air ions exhibited prominent peaks and valleys, with peaks primarily distributed from 01:00-07:00, and valleys distributed around 12:00. Seasonal change was significant:the summertime concentration of negative air ions was 2437 ions/cm³, which is twice that of the springtime level. The concentrations of negative air ions for different ecosystems were markedly different. Forests displayed higher concentrations than other ecosystems, such as grassland and farmland. The main factors affecting negative air ions were found to be temperature and humidity. Negative air ion concentration decreased with increasing temperature and increased with increasing humidity. This study revealed that the forest ecosystem has the strongest service capacity of negative air ions. In addition, the service capacity of arbor greenbelts is greater than that of shrub and herb greenbelts. In urban centers, the greater the area of forests and arbor greenbelts, the greater the service capacity of negative air ions.