Based on the observational atmospheric turbulent data obtained in the south of Tianjin City in February 2006, the characteristics of turbulent transfer and its temporal evolution have been analyzed during an advection fog process. The results show that the absolute value of stability parameter is mainly in the range less than one, and the unstable condition is dominant during the advection fog. Before the fog formation, the atmosphere is slightly unstable; heat transfer in horizontal and vertical directions intensifies in a short period; the horizontal heat transfer is much larger than the vertical transfer. In the stage of fog formation, it turns to be stable, with turbulent momentum and heat fluxes being weak in every direction. During the fog, the atmosphere is mainly unstable with the multi-peak undulation characteristics for the temporal variations of stability parameter, turbulence momentum, heat fluxes, and the ratio of heat fluxes in horizontal and vertical directions. The slight instability gradually changes to slight stability as the fog dissipate. The lower atmosphere is unstable after fog with the momentum and heat fluxes showing a diurnal variation feature (large at noon and weak at night).  During the fog process, horizontal heat fluxes decrease quickly with the stability parameter increasing. The variations of the standard deviations of wind speed with the stability parameter satisfy the 1/3 power law. Under the stable condition, the ratio of heat fluxes in horizontal and vertical directions is approximately equal to 2, and the standard deviations of wind speed increase with stability while the standard deviation of potential temperature decreases with stability. Both the friction velocity and the ratio of heat fluxes in horizontal and vertical directions show multi-peak distributions during the fog, with their peaks reaching 1.2 m/s and 50, respectively.