Abstract: Based on the conventional high-altitude and ground observation data and the meteorological data of automatic station, this paper analyzes the initial frost weather process from August 29 to 30, 2017 in Chifeng City. The results show that the first frost weather is a typical north air flow behind the high trough. At 20:00 on August 28, 2017, the high altitude 700 hPa situation showed a trough and ridge pattern in the middle and high latitudes of the East Asian continent. Chifeng City was in the northerly air flow behind the cold vortex bottom and north of the high altitude front area. In the key area, 45 ～ 50° N and 110 ～ 120° E, the intersection angle of isotherm and contour line was large, forming a strong cold advection, which was conducive to the transmission of cold air in high latitudes to Chifeng City, which was the main reason for the frost weather, The clear sky radiation cooling and the special terrain of low in the east and high in the west are also important factors in this frost weather.