A large range of 5-day advection-radiation fog weather occurred in Shandong Peninsula from 1 to 5 January 2017. By analyzing the large-scale circulation, the temperature and humidity field, and surface and upper meteorological elements, the formation, maintenance, and dissipation of the fog are revealed based on automatic weather station data in Shandong, sounding data and wind profile radar data in Qingdao as well as conventional observation data and NCEP/NCAR reanalysis data. The results are as follows. The flat atmospheric circulation in middle and high latitudes and the static atmospheric vertical structure are the background conditions of this fog. The density change of the water vapor resulting from the phase change during its transfer causes the phase change of the fog. Two weak cold front processes significantly enhance the intensity of the fog and expand its effect range, and also make the advection fog develop into a radiation one. When the moisture on the low layer declines and the easterly wind speed on the boundary layer increases and destroys the stable atmospheric stratification, the fog gradually dissipates.