Cold surge is one of main features of East Asian winter monsoon,and can lead to high influence weather,for example,low temperature and chilling injury.The cold surge over the northern South China Sea(SCS) is closely associated with the outbreaks of cold air influencing most part of China,and results from the interaction between the mid-high latitudes circulation and the lower latitude circulation.Southward movement of cold surge shows two kinds of gravity wave,which are influenced by dynamical effects of large-scale topography significantly.The high-frequency inertia-gravity and Kelvin waves are correspondence to the front of cold surge events and the maximum northerly center of cold surge,respectively.In this paper,based on the atmospheric circulation model NCAR CAM3,the influences of altitude changes of the Tibetan Plateau on the cold surge over the northern South China Sea and circulations have been investigated by comparing the results between the sensitivity experiments and the control experiment.The results show that the flow around topography is closely associated with the formation of the Aleutian low and East Asian trough,and when the large scale topography does not exist,the Aleutian low and East Asian trough disappear.The changes of topography altitude does not influence the formation of cold high over the continent,but it can influence its intensity,showing that the intensity of continental cold high decreases with the decrease of topography altitude of Tibetan Plateau.The large scale topography plays an important role on the planetary mean trough and ridge over mid-high latitudes.The decrease of topography altitude leads to the decrease of meridionality of circulation over mid-high latitudes,which is not conducive to cold air southward and further influences the intensity and frequency of cold surge events.When the topography altitude is halved,due to the eastern part of the continent is relatively flat,the intensity of the northerly over the northern SCS increases,leading to the increase of occurrence frequency of cold surge over the northern SCS.When there are not topography,the meridionality of circulation over mid-high latitudes in East Asia decreases significantly,and the southward movement of cold air decreases obviously.Meanwhile,the southward movement of Kelvin wave triggered by the Tibetan Plateau disappears,inducing the decrease of northerly over the northern SCS and the significant decrease of occurrence frequency of cold surge over the northern SCS.