Using the ozone sonde data derived from GPSO3 ozone sounding system and the NCEP reanalysis data,this paper investigated the persistent ozone peak phenomenon and the abnormal ozone content in the range of 10-14 km height over Beijing in winter 2008 by analyzing the weather situations,atmospheric circulations,upper potential vorticity variations and changes of tropopause height.Results show that,during the special period when there was a snow disaster in South China in 2008,the main reasons of phenomenon of the ozone peak and abnormal content are the strong downward movement of stratospheric air and the stratosphere-troposphere exchange(STE).The ozone downward transport from stratosphere to troposphere is due to the special weather background,including the long time maintenance of the Ural blocking high,the stable existence of the transverse trough between Lake Baikal and Lake Balkhash,and the long-term maintenance of the cut-off low lying on the eastern of the Caspian Sea,leading to the stably southward movement of cold air to affect the vertical ozone distribution over Beijing.Synchronously,with appearance of the subtropical westerly jet,Beijing is located at the left side of the jet entrance areas,and there is a strong convergent and downward movement in upper levels,which is helpful to the air downward transport from stratosphere to troposphere.To sum up,the phenomena of ozone peak and abnormal ozone content shows that the movement of stratospheric air and the STE is much more active over Beijing under the influence of cold air process.