Urban green space is an important components of ecosystem, therefore, studying the evolution of urban green space and its ecological benefits, revealing the mechanism between them can provide a theoretical basis for improving the ecological environment and assisting urban sustainable development. With the help of envi, ArcGIS, ArcView and other relevant softwares, the remote sensing image maps of Hefei Municipal Area is interpreted and classified using the supervised classification. and the evolution of green space and its ecological benefits in carbon sequestration, air purification, soil and water conservation, heat island effect and so on are analyzed. The results show that: (1) the area of green space in Hefei Municipal Area is reduced by 516.59 km² while most of them have been converted to the construction land, which accounts for 74.9% of the construction land area in 2020. At the same time, unvegetated areas and low vegetated areas have increased by 255.5 km² while the urban landscape pattern varies with different functional zoning, and is constantly developing towards fragmentation and heterogeneity. (2) The total ecological benefits of green space in Hefei Municipal Area decreased by 420 million yuan, whil carbon sequestration, air pollutant removal and storm runoff reduction decreased by 177 million yuan, 5.489 million yuan and 261 million yuan respectively. In the meantime, the demand for ecosystem services have increased to 700 times; (3) With the expansion of urban space, the original high-temperature areas around the central urban area and Changjiang West Road spread unevenly to most parts of Hefei Municipal Area Meanwhile, the surface temperature in the study area increased with the decrease of regional vegetation coverage, showing an obvious negative correlation. The area of urban green space in Hefei urban area decreases with the advancement of urbanization, and its ecological benefits also decrease, resulting in problems such as the reduction of ecosystem service capacity, the imbalance between ecological supply and demand, and the strengthening of heat island effect.