Abstract: Objective To investigate anatomic relationships between the internal jugular vein and the common carotid artery under CT enhancement scan at a different plane.Methods To collect the anatomic relationships between the internal jugular vein and the common carotid artery at the high plane（the upp-er edge of the thyroid cartilage）、median plane（the level of the cricoids ca-rtilage）in our hospital patients since January 2010 to July 2012,all patients were checked by CT enhancement scan. Results At the high plane,the internal j-ugular veins are mainly posterior and posterolateral position（78.6%-83.9%）,the relationships with the common carotid artery are mainly partially overlap（70.5%-71.4%）.While at the median plane ,the internal jugular veins are mainly anterior and anterolateral position（72.3%）,the relationships with the common carotid artery are mainly parallel（56.2%-63.4%）. Conclusion Operating the internal jugular vein cannulation at the median plane had higher success rate and reduced more complications than the high plane.