Abstract: In this paper, a numerical model is established to study the life cycle of radiation fog.The variables predicted in the model are the wind velocity, the temperature,the specific humidity, the liquid water content and the concentration of fog droplets.New sets of parameterization formulae are adopted for the microphysical processes of fog and the turbulent exchange coefficients. The absorption and the emission of infrared radiation by water vapor and water droplets are considered, also the scattering of near infrared radiation by fog drops.The fog model is used to simulate a representative instance of observed fog process the results show that the model is practicable.