Based on the artificial and automatic observed data at Nanchang Changbei Airport, the conventional surface observations and sounding data provided by China Meteorological Administration, and the hourly air quality index (AQI) data of 9 stations in Nanchang from China National Environmental Monitoring Centre, 76 fog events from September 2013 to September 2017 at Changbei Airport are classified and statistically analyzed. The results show that the fogs of Changbei Airport mainly occur in November to May, they mostly form in the period 04:00-10:00 BT, and dissipate in 06:00-14:00 BT, mostly lasting less than 4 hours. Rain fog occurs most, followed by radiation fog and advection-radiation fog, and advection fog appears the least. The fogs of Changbei Airport are closely related to the air quality. The AQI often has an upward trend before fog occurs, with the value ranging within 54-100. The AQI in rain fogs is the largest, often accompanied by mild to severe pollution. Rain fogs mainly occur between the low-level warm and wet shear lines and the inverted trough on surface in autumn, winter and spring. They often form after continuous light rain or drizzle.The visibility maintains at a low level, mostly 600-800 m, for a long time before the fogs are formed, and keeps stable. Radiation fogs usually occur in the weak high pressure from late autumn to early spring of the next year. They often form in the morning after rain stops and the sky clears, and gradually dissipates after sunrise. They last longer if the bottom of inversion layer is higher. Radiation fogs form after the gradual increase of humidity, and the visibility is mostly 200-600 m. Advection-radiation fogs mainly occur in the weak warm advection behind the high pressure moving east to the sea in early winter and spring. They form generally after the rapid increase of humidity, and the visibility is mostly 200-700 m. Advection fogs usually occur in the surface saddle pressure field south of the low-level shear line in spring and summer. They are generated after the end of rain induced by a north lift of the shear line, and the visibility is mostly 400-600 m.