Abstract:A sustained fog haze event that occurred in early December 2013 in Yancheng was analyzed based on surface meteorological parameters, NCEP reanalysis data (1°×1°), and air pollutants concentration. The study focus lies in circulation background, surface meteorological elements and atmospheric stratification feature, as well as thermodymamic condition and pollution. The results show that there were weak cold air forces in middle high level in early December with zonal circulation at 500 hPa. The breezed surface layer was the favorable circulation background for the formation of fog haze. The maintenance of stable stratification characteristics, high inversion intensity and continuous lower mixed layer were responsible for the sustained fog haze briefly. In addition, the weak sinking motion, positive divergence and negative vorticity were the dynamic factors for the sustain development of fog haze. The long distance transport of pollutants played a certain role in the concentration increase of pollutant particulates according to the backward trajectory types and the monitored fire spots. Finally, the non linear regression formula of visibility, humility and PM2.5 concentration was established, which is better for visibility forecasting and provides a favorable basis for the operation of fog haze forecasting.