Abstract:In the present study, we discussed the interactions between surface weather types, ground weather situations, meteorological elements and the concentration of PM2.5 and PM10 in the haze days in Nanjing 2012~2014 by using synoptic meteorology principle. The results showed that most of the haze pollutions in Nanjing were slight and mild, mainly occurred in winter and seldom in the summer. The haze days occurred easily when the relative humidity between 50%~80%, especially 70%~80%. Nearly 87.6% of the haze days occurred in the case of wind speed 4m/s or less and wind direction northeast to southeast. The haze days frequently presented in the uniform pressure field, high pressure control, and the back of the high pressure, while in the conditions of under controlled by the subtropical high pressure, low pressure trough and typhoon, it was rare. The ratio of mass concentrations of PM2.5 in PM10 was proportional to the strength of haze pollutions. The results of trajectory clustering analysis by HYSPLIT4 mode showed that in the medium and heavy haze days in Nanjing, it was mainly affected by the local pollution and sources from northeast China and southeast of Nanjing.