Abstract: To improve the accuracy of radiation fog nowcasting at Tianfu International Airport, this study analyzes the characteristics of temperature stratification and humidity condition of four radiation fog processes at Tianfu International Airport by using data from microwave radiometer and other sources, and explores the application of microwave radiometer products in radiation fog monitoring. The results show that the temperature profile product can be used to analyze the strengthening and weakening of temperature inversion layer, which has dication significance for the decrease and increase of runway visual range (RVR). The liquid water path tends to increase during the fog formation stage, and when RVR is less than 550 m and at the end of the fog event, the liquid water path often shows an "upward－downward" trend. Absolute humidity can be used to determine the humidity conditions at the airport before fog formation, and the absolute humidity at the top of the planetary boundary layer (2 km) is usually 3 g/m³ or higher before fog formation. Relative humidity greater than 90% corresponds to the presence of distinct cloud layers, and the thickening of the high relative humidity area in the near-surface layer corresponds to fog intensification. When RVR is less than 550 m, the high relative humidity area below 2000 m tends to experience an explosive thickening.