Abstract: Using the NCEP/NCAR reanalysis data and Climate Prediction Center daily temperature data, the distribution characteristics of 500 hPa cold vortex in the northern hemisphere winter are studied by automatic machine identification and visual method. Based on information flow causality theory, the relationship between cold vortex in Northeast Asia and other active regions in the northern hemisphere and the extreme cold events in China is investigated. According to the variations of cold vortex cumulative days along longitude, four active subregions are identified. It is found that the frequency of cold vortex activity in the northern hemisphere winter from large to small is 37.7% in the Atlantic-European region, 22.35% in the North Pacific region, 20.95% in Northeast Asia region and 13.77% in the North America-Greenland region. The averaged central intensity of cold vortex in the North America-Greenland region is the strongest (493 dagpm), while that in the Atlantic-European region is the weakest(514 dagpm). On interannual scale, the activities of cold vortex in Northeast Asia are relatively independent. To some extent, only cold vortex days in the North America-Greenland in January are the unstable sources of the interannual variations of cold vortex activities in Northeast Asia in February. The dynamic characteristics analysis of strong cold vortex years shows that the cold vortexes in Northeast Asia and the North America-Greenland are closely related to positive phase of the NAO, the cold vortexes in the North Pacific are closely related to positive phase of the NPO, while the cold vortexes in the Atlantic-European region correspond to negative phases of the NAO and NPO. The cold vortexes in Northeast Asia are closely related to extreme low temperature events in China. Four kinds of extreme cold events are defined by cluster analysis. It is found that the northeastern-northern type, the northern type, the south of the Yangtze River type and the mid-eastern type are accompanied by strong cold vortex activities in Northeast Asia.