Circulation situation, characteristics of surface meteorological elements, structure of atmospheric boundary layer and air pollution status of the longlasting foghaze event in Jiangsu Province during 12-16 January 2013 are analyzed by using the FNL analysis data, data on pollutant particle concentration and conventional meteorological data. The results indicate that steady upper air circulation situation, warm advection of middlelow layers and stable distribution of surface pressure field are favorable for haze to occur in terms of circulation features. Continuous and slight changes of pressure gradient, slow wind speed, increase of relative humidity as well as the PM2.5 and PM10 concentrations are beneficial to the formation and development of haze. Temperature inversion is observed in low layers during the haze event. The height of mixed layer is inversely correlated to AQI. Lower mixed layer height corresponds with higher AQI, more serious pollution and lower visibility. The increase of relative humidity and enrichment of PM2.5 concentration in contaminant particles lead to the decrease of visibility and continuous pollution while strong wind and low temperature caused by severe cold air is responsible for the important dynamic mechanism of quick erasion of particulate matter. The pollution of Nanjing mainly originates from the Yellow Sea, Anhui Province, and the pollution from the north and local atmospheric pollution.