The area size and intensity of 500hPa north polar vortex and four quadrants are estimated from 1950 to 2002 based upon the 53-year NCEP/NCAR reanalysis monthly mean geopotential height data.The relationship between the polar vortex and air temperature in China is analysed.Results show that there is a negative correlation between the annual and seasonal areas of polar vortex and the air temperature in the same period,especially for year and winter,and from January to December,the above negative correlation has a trend from weakening to strengthening.The association of the air temperature with the intensity of polar vortex is not so strong as with area,in autumn and winter the positive correlation occurres over some regions,and from January to December,the negative correlation shows an opposite trend from strengthening to weakening.Finally,the influence of polar vortex on the subsequent air temperature in China is discussed by using SVD.It is found that the polar vortex has negative effect on the subsequent air temperature,but there is some difference in different seasons.For example,if the vortex in region Ⅳ shrinks anomalously in winter and the intensity of north polar vortex remarkably strengthens,the next spring air temperature will become higher in Northeast China and the area north of the mid-and low-reaches of the Yangtze River.When the size and intensity of the vortex in region Ⅰ are anomalously large in spring,summer air temperature will be lower than normal in Southwest China,the coast area of South China,and the Hetao region.Prominent weakening of the north polar vortex in spring and remarkable shrinking of the vortex over region Ⅰ in summer lead to the rising of autumn air temperature in South China.