Abstract: Based on the classification data of landuse pattern from Landsat, nighttime light image data, automatic meteorological stations data and atmospheric boundary layer (ABL) sounding data, the representative stations of urban area, rural area, and lake were chosen for the urban heat island (UHI) analysis. The characteristics of UHI in Suzhou in January 2015 were studied in this paper. The result showed that: (1) UHI intensity was weak at daytime, which was less than 10℃ from 09 am. to 05 pm., with the minimum of only 02℃. UHI intensity was strong at night, which maintained above 12℃, with the maximum of 17℃. (2) The temperature difference between urban area and lake was positive at daytime and negative at night. Temperature variation rate of urban stations was about 02℃/h faster than that of lake stations. (3) The shape of heat center was irregular and has a large range at daytime, and the temperature difference between urban and rural area was small in Suzhou. However, at night the temperature difference between urban and rural area maintained at about 15℃,and a single, closed and stable heat center was formed, which was in correspondence with that in downtown area. The northwest wind was prevalent on the ground in winter, and Taihu lakeland wind was obvious in Suzhou. The combined action of lakeland wind and prevailing wind jointly transferred the urban thermal plume to the southwest. (4) The difference of virtual potential temperature profiles between urban and lake was small, and unstable ABL developed both in urban and lake area at daytime. However, at night, unstable ABL profiles were still maintained in urban area, and stable ABL profiles developed in lake area. In the meantime, the phenomenon of wetisland near ground surface was obvious. (5) The influence of UHI in vertical direction has significant diurnal variation, which was less than 40m at daytime, and more than 200m at night.