The genesis and dissipation mechanisms of three radiationadvection fog events in Chengdu of December 2016 are analyzed, using the data from wind profile radar, microwave radiometers, automatic weather stations, secondlevel sounding data and NCEP/NCAR reanalysis data (1°×1°). The results indicate: (1) the northwest airstream at 500 hPa, maintenance of dry layer at 700 hPa and weak wind below 1.5 km height were beneficial to the rapid radiation cooling near the ground, forming the inversion layer and offering thermal conditions for the formation of the fog. (2) No movement or less movement in vertical direction offered dynamic conditions for the formation and development of fogs. The convergence caused by weak southwest warm and moist air (≤4 m/s) near the ground in Chengdu provided ample water vapor conditions for the formation of the strong fogs. (3) The coexistence of surface inversion layer and dewpoint inverse layer (lower than the height of the inversion layer) better indicates the occurrence of the fogs. (4) In the afternoon, double inversion layers and weak winds near the surface were important reasons for the maintenance of radiationadvection fogs. (5) After the southwest warm and moist air disappeared or water vapor convergence removed out of Chengdu, the disappearance of the nearsurface inversion layer or entrainment of dry air at the top of fogs is the cause of the final disappearance of the radiation advection fogs.