Abstract: Wetlands are indispensable ecosystems on Earth. Exploring their area changes and ecological security characteristics is of great significance for maintaining regional ecological balance, safeguarding biodiversity, and promoting sustainable development. This study took the middle reaches of the Yellow River as the study area, analyzed the spatial and temporal change characteristics of wetlands in this region based on the GlobeLand 30 surface cover data from 2000 to 2020, constructed the ecological security evaluation index system by using the Pressure-State-Respnse model, evaluated the ecological security of wetlands in the study area, and revealed the spatial autocorrelation of the ecological security by calculating the Moran index, and gave corresponding countermeasures. The results showed that the land cover structure of the middle reaches of the Yellow River remained basically unchanged from 2000 to 2020, with cropland dominating, followed by grassland and forest, and wetlands and water bodies accounting for a relatively small proportion of the area. There was a trend towards a decrease in the area of cropland and grassland, an overall increase in the area of forests, a slight overall decrease in wetlands and a slight increase in the area of water bodies. We analyzed the amount of land cover transfer in the study area, and found that the transfer of wetland to cropland was more serious, as high as 36.89% from 2000 to 2010, and slightly decreasing from 2010 to 2020, accounting for 19.21%. In the past 20 years, the ecological security of wetlands in the middle reaches of the Yellow River had deteriorated, and the number of insecure areas had gradually increased. There was an obvious positive correlation between wetland ecological security, but the degree of spatial aggregation had decreased. In conclusion, it is necessary to strictly control wetland conversion, strengthen ecological restoration, optimize spatial planning and implement cross-regional collaborative management to ensure the sustainability and ecological health of wetlands in the middle reaches of the Yellow River.