Based on the conventional meteorological observation data and the automatic observation data of the airport, the radiation fog process generated under the background of a mid-level jet stream at Shuangliu Airport on January 5, 2023 was analyzed. It was found that on the 4th (before the process), daytime precipitation induced by wave disturbances led to high humidity and low temperatures near the surface, while dry and cold advection on the southern side of the mid-level jet stream caused cooling and subsidence at night. By 08:00 on the 5th (during the process), the combined effects of warming from mid-level subsidence and low-level warm advection resulted in mid-level cooling and low-level warming with reduced humidity. The process disrupted the cloud-top inversion, thinning the cloud layer and enhancing radiative cooling, ultimately leading to radiation fog formation. During the process, surface moisture conditions were more favorable in the southern part of Shuangliu Airport. At the same time, the surface wind maintained a stable southerly wind around sunrise. The wind speed increased to 1~2 m/s, and the disturbance mixing was strengthened, which was also one of the reasons why the fog mainly appeared in the morning of sunrise and affected the south-central part of the airport.