Under the background of global climate warming and rapid urbanization，extreme heat events have be‐ come a significant threat to human health and social sustainable development，particularly in Yangtze River Delta （YRD），a densely populated and economically developed region. Based on meteorological observations from 1961 to 2020，this study systematically analyzes the trends of daily maximum temperature，daily mean tempera‐ ture，and heat wave indices in the YRD. Additionally，sensitivity experiments using the WRF model are conduct‐ ed to assess the impact of urban land use on extreme high temperature events. The results show that：（1）Both daily maximum temperature and daily mean temperature in the YRD have exhibited significant upward trends over the past few decades，with the increase in daily maximum temperature［0. 194 ℃·（10a）-1］being more pro‐ nounced than that in daily mean temperature［0. 187 ℃·（10a）-1］. Pettitt test results indicate a significant change point in 1993，with temperatures showing a downward trend before the change point and shifting to an upward trend after the change point.（2）The frequency，duration，and intensity of heat waves have significantly in‐ creased at rates of 0. 190 time·（10a）-1，0. 475 d·（10a）-1，and 0. 772 ℃·time-1·（10a）-1，respectively，indicating that the frequency，duration and intensity of heat waves increased significantly. The change point for heat wave indices lags behind that of temperature change point and occurring in 2000. It showed an insignificant downward trend before the change point，and turning into a significant upward trend after the change. Intensity of heat wave increasing at a much higher rate than frequency and duration.（3）Urbanization has a significant impact on tem‐ perature and heat waves. The daily maximum temperature［0. 243 ℃·（10a）-1］and daily mean temperature ［0. 261 ℃·（10a）-1］of urban stations being significantly higher than those of rural stations［0. 171 ℃·（10a）-1、 0. 167 ℃·（10a）-1］，suggesting that urbanization has an amplifying effect on warming. The increasing trends of heat wave indices at urban stations are also significantly stronger than those at rural stations，indicating that ur‐ banization may enhance the occurrence of heat waves.（4）The WRF model can effectively simulate the hourly variation of temperature，and urban land use significantly affect urban station temperatures，especially during hot days，with a more pronounced effect at night. Urban underlying surfaces enhance the surface energy changes of urban stations during hot days by changing the surface energy budget（such as sensible heat flux，latent heat flux and surface heat storage），which intensifies the temperature during hot days，while rural stations are less affect‐ ed by urbanization. This indicates that the urbanization process has a more obvious impact on extreme high tem‐ perature events in urban areas. The frequency，intensity and duration of heat waves in the Yangtze River Delta re‐ gion have shown a significant upward trend in the past few decades，and urbanization has played an important amplifying role in this. With the further development of urbanization，the frequency and intensity of extreme high temperature events are likely to increase further，highlighting the necessity of developing effective adapta‐ tion strategies and mitigation measures.