Abstract: Taking Yuxi City as the research object, combined with the actual situation and data of its ecological environment, this paper evaluated the importance of ecosystem service functions in Yuxi City and explored the internal mechanism of its importance pattern formation.The results showed that the importance of ecosystem service functions in Yuxi City was mainly extremely important, with an area of 13 556.94 km², accounting for 90.74% of the total area of Yuxi City; the distribution of general important areas was relatively small, located in the southwest of Yuxi City, mainly in Yuanjiang County;the distribution of important areas was relatively scattered, mostly in the eastern part of Yuxi City, mainly distributed in Hongta District, Jiangchuan District, Haitong County, and Chengjiang City;the extremely important areas were widely distributed, covering various counties and districts in Yuxi City, mainly distributed in Eshan County, Yimen County, Xinping County, and Huaning County;among different importance levels, the total area of cultivated land and forest land accounted for a relatively large proportion. The proportion of cultivated land area was negatively correlated with the importance level of ecosystem service functions, while the proportion of forest land area was positively correlated with the importance level of ecosystem service functions. As the importance level changed, the two showed a pattern of one declining and the other growing.

Key words: importance of ecosystem service functions, water source conservation, soil and water conservation, biodiversity maintenance, Yuxi City