Abstract: A severe haze pollution occurred in the Yangtze River Delta during December 1 st-9 th,2013. The formation,characteristics and potential sources of this haze pollution were explored by using the aerosol products of CALIPSO/CALIOP and COMS/GOCI satellite data, CE318 sun photometer, ground meteorological data and HYSPLIT backward trajectory model. The six typical cities of the Yangtze River Delta were dominated by this haze pollution. The air quality was in severe pollution and the air quality index (AQI) and the value of PM2.5 were higher than those of usual case. The analysis of CALIPSO/CALIOP satellite data indicated that the aerosol mainly existed in the level from the ground to 2 km above, the proportion of spherical aerosol in haze aerosol was higher than that of non-spherical aerosol,and the proportion of large size aerosol particles in haze aerosol was higher than that of small aerosol particles. The analysis results of the CE318 data and HYSPLIT model show that this haze pollution was not only influenced by the local aerosol emissions but also influenced by the outer sources of aerosols, and such factors as continuous low wind speed,high relative humidity and no precipitation during the haze pollution led to the widespread,long-time and severe pollution event in the Yangtze River Delta.