Abstract: For better understanding the change behavior of temperature in urban and rural shallow soils,two long-term observation stations were built and a large amount of measurement points were also selected in urban and rural areas of Nanjing city.By analyzing the obtained soil temperature data,it is found that the average annual temperature of urban soil is 19.23℃.It is 2.02℃ higher than that of the rural soil.Such result reveals an obvious dry island effect in the urban soil.The soil temperature differences between urban and rural areas show evident temporal-spatial characteristics.In temporal pattern,the average daily temperature difference between urban and rural soils ranges from 0.37 to 3.83℃, and shows significant variability over short time scales.The average monthly difference ranges from 1.34 to 2.9℃.The minimum and maximum monthly differences occur in November and July respectively.The average seasonal difference ranges from 1.53 to 2.45℃.The minimum and maximum seasonal differences occur in summer and autumn respectively.In spatial pattern,the critical affected depth of daily synoptic events on soil temperature is approximately 60cm.Below this critical depth,there is a time delay to the effects of synoptic events.An evident hysteresis(about one month delay per 100cm depth increment)can be observed.Within the 0～300cm depth,the temperature difference between urban and rural soil generally increases as the depth increases.In addition,it is found that the soil temperature in urban area is much more variable than that observed in rural area.