In this paper, characteristics of variation in different physical elements in the key area and affected areas of the cold activities in East Asia during winter are, studied. Significant one-week and quasi-40-day oscillations are observed, which have close relation to the cold air activities. It is found that the strong cold air activity is mainly under the control of the low frequency oscillation. The phase of the quasi-40-day oscillation of temperature in the key area is about 5 days earlier than that in the affected areas (central China) and its amplitude responds quite well to the strength of cold air.This provides a good reference for the forecasting of cold air. Besides, the cold air may show different characteristics at different stages of its southward propagation. In the end, the relation between the intensification and westward extension of the upper easterly jet in the lower latitudes in East Asia and the strong cold air activities is discussed.