Abstract: Based on the daily observational temperature data, monthly precipitation anomalies and statistical yearbook data in Nanjing, the climatic response of crop yields to summer cumulative high temperature was analyzed. The results show that summer cumulative high temperature in Nanjing has presented an increasing trend since 1949. The linear growth rate of summer cumulative high temperature over the last 30 years is almost 8 times that over the last 60 years (2.88℃ vs. 0.35℃ per year). Summer cumulative high temperature has significant negative correlations with summer and autumn grain yields, showing a correlation coefficient of -0.66 and -0.62, respectively. Although there is also certain negative correlation between summer cumulative high temperature and the yields of oil-bearing crops, the correlation coefficient is not as significant as the former two. Crop yields show no response to summer cumulatire high temperature.