Abstract: An analysis of the energetics of a cold vortex in Northeast China is performed. The approach is based on the computation of anenergy flow for and open at mosphericregion in which this cold vortex is the major synoptic-scale feature. Following results have been obtained. The conversionterm Ae→Ke acts as a main source of the eddy kinetic energy of the cold vortex. When the coldvortex is in developing period, the boundary inflow of the eddy kinetic enery is also important. The major sink of the eddy kindtic energy is Ke →Kz, the Re and the boundary out flow after the mature stage of the cold vortex are the secondary important. The absolute value of the change of the eddy kinetic energy in the middle and upper tropo sphere is larger than that in the lower tropo sphere layer, but the result is contrary to the relative variability. The Ae→Ke occured mainly in the 700-300hPa, the contrary conversion from Ke occured mainly in the 700-300hPa, the contrary conversion form Ke into Ae is appeared in the upper at mosphere above 300hPa.