Abstract: Vegetation growth is not only influenced by climate, but also serves as an indicator of climate′s regional ecological impacts.Against the backdrop of global warming, a significant increase in extreme high-temperature events is affecting vegetation growth processes.Current research primarily focused on the effects of temperature extremity, with less consideration for diurnal temperature asymmetry and its differential impacts on vegetation.This study took the Yangtze River Basin, a region frequently affected by extreme climate events, as a study area.The diurnal asymmetric characteristics of extreme temperatures from 2001 to 2022 were quantified, based on the Expert Team on Climate Change Detection and Indices (ETCCDI) metrics.Concurrently, the interannual trends of summer vegetation were analyzed using the Google Earth Engine (GEE) platform and trend analysis methods.Subsequently, the Geodetector model was employed to explore the relationship between summer vegetation dynamics and diurnal extreme temperatures, revealing the varying impact mechanisms of temperature across different diurnal periods, months, and years.The results indicated that both vegetation indices and extreme temperatures in the basin showed an overall increasing trend with significant spatial heterogeneity.At the interannual scale, the influence of temperature on vegetation was most pronounced in 2022, while at the monthly scale, August′s temperatures had a more significant impact than other months.Critically, the intensity of nighttime extreme temperatures in the summer had a significantly greater effect on vegetation than that of daytime extremes, whereas the frequency of diurnal high-temperature events had a lesser impact.This research revealed the differential stress on summer vegetation health caused by diurnal asymmetric warming, highlighting the ecological risks of nighttime heat.These findings provided a scientific basis for adaptive management of regional vegetation under climate change