An increasing linear trend is found in wintertime hazy days in Jiangsu province in the past 50 years. A transition from the negative to the positive phase is found around the end of 1970s in departures of wintertime hazy days from the 50-yr mean. Such a transition may be related to abrupt climate change in East Asia. In this paper, using the data of meteorological stations in Jiangsu and the NCEP/NCAR reanalysis, the feature of the decadal variability of wintertime hazy days in Jiangsu is investigated with discussions of its links with the interdecadal climate variations. Results indicated that during the period of low occurrences of wintertime hazy days in Jiangsu, the anomalous geopotential heights at 500 hPa in the mid-high latitudes from Europe to Asia are alternatively with positive-negative-positive centers, i.e., the positive anomalous geopotential heights are observed respectively in regions of Urals Mountains and around Aleutian Islands while the negative ones are found in regions around Lake Baikal. This "two ridge-one trough" pattern facilitates the southward migration of the cold air, intensifying the winter monsoon in East China, and henceforth leading to the evaporation and diffusion of atmospheric moisture and pollutants. This situation is believed not to be conducive to the occurrence of haze, especially in the period before 1979. However, in the period of 1980-2010, the circulation pattern looks opposite to those before 1979,which facilitates a weak winter monsoon, inducing more haze events in Jiangsu province in boreal winter. In addition, a possible relation is found between Jiangsu winter haze days and warming trends in this region as a result of the local response of the atmosphere to the thermal forcing due to warming trends there.