In global warming, the influence of lakes on climate change in surrounding areas has attracted extensive attention from many scholars. Based on 40 years of observation of the daily mean temperature, maximum temperature, and minimum temperature of 16 meteorological observation stations around Hongze Lake, we analyzed the trend and characteristics of temperature change in the area around Hongze Lake from 1981 to 2020. The Mann-Kendall trend analysis method and mutation detection method were used for the analysis. The daily mean, maximum, and minimum temperatures have fluctuated but increased. The daily minimum temperature showed the largest increase (0.55℃/10 years). The daily mean, minimum, and maximum temperatures changed significantly with the seasonal variation, and the warming trend in spring was most significantly observed, followed by those in winter and summer. The historic increase in temperature in autumn was the least significant. The abrupt change points of daily mean, minimum, and maximum temperatures were observed in 1996. Fluctuation became more severe and frequent after such abrupt changes. The increase in temperature in seasons was significant before and after 1998. The abrupt change air temperature of Hongze Lake was observed most frequently in winter, followed by autumn but in spring and summer, there were no such outliers observed in temperature. The closer the area to Hongze Lake, the temperature changes became smaller, the minimum temperature became higher, and the maximum temperature became lower. This verified the climate regulation effect of Hongze Lake on the surrounding area. The research results provide a reference for creating a protocol for possible natural disasters in the future and for transportation in water and agricultural structure adjustment.