Regional green spaces are crucial for maintaining the integrity of urban ecological functions and controlling the uncontrolled expansion of construction land, providing significant ecosystem services. This study focuses on Nanjing City, analyzing the distribution changes of regional green spaces in 2005, 2010, 2015, and 2020 based on the large-scale impervious surface index. The evolution of ecosystem service value for regional green spaces was calculated using the equivalent factor method. Additionally, simulations of the distribution and ecosystem service value of regional green spaces for 2030 were conducted using the Markov-FLUS model, incorporating scenarios of inertia development, green space protection, and ecosystem service protection. Results indicate that from 2005 to 2020, the area of regional green spaces in Nanjing decreased from 753 km2 to 695 km2, a reduction of 58 km2, with a corresponding decrease in ecosystem service value by 262 million yuan, showing a year-by-year decline. The distribution of regional green spaces is uneven, with higher proportions in Jiangning District, Lishui District, Pukou District, and Liuhe District, which contribute significantly to ecosystem service value. Compared to the inertia development and regional green space protection scenarios, the ecosystem service protection scenario results in an increase of 43 km2 in regional green space area and a 199 million yuan increase in ecosystem service value. This scenario is the most beneficial for sustainable development, indicating that implementing ecological restoration under ecological control can significantly enhance the ecosystem service value of regional green spaces.