Abstract: Using the ground meteorological observation data of Xujiahui and Yangshan stations in Shanghai from 2008 to 2016, the diurnal variations of temperature in Shanghai and Yangshan harbor area were analyzed. The results show that: 1) There are obvious seasonal differences in diurnal variation of temperature between urban area and harbor area. The diurnal variation range of temperature in urban area is larger than that in harbor area in all seasons. The change of temperature in harbor area, due to the infection of ocean, is gentler. 2) The maximum temperature rising (cooling) range of the harbor area is lower than that of the urban area, and the change is gentler. The temperature rising and cooling changes in urban and harbor areas are asymmetric, and the temperature cooling changes more slowly than the temperature rising. 3) The maximum temperature rising changes in the urban areas are relatively concentrated throughout the year, and scattered in the harbor area. The maximum temperature cooling appearance rate of urban and harbor area shows obvious asymmetry around the peak value, and the larger incidence in the urban area is concentrated on 16:00 to 18:00 BT, while the harbor area on 18:00 to 20:00 BT. 4) the appearance of the highest and lowest temperature have double-peak structure, there is higher occurrence rate of the highest temperature on 13 and 20 BT, while there is higher occurrence rate of the lowest temperature on 05 and 20 BT. There is significant difference in the lowest temperature occurrence rate in each season.