【Abstract】 Objective To compare the variance of internal jugular vein and carotid artery after inserting laryngeal mask and To assess the clinical value and safety of real-time ultrasound-guided technique for internal jugular vein catheterization with laryngeal mask ventilation. Methods Eighty patients with laryngeal mask ventilation were randomly allocated to control group(n=40) and ultrasound-guided group(n=40). before inserting laryngeal mask, every patient’s diameter of vessels, horizontal distance and overlap between internal jugular vein and carotid artery at three different level (low level: 1cm above supraclavicular fossa; middle level: junction of the two heads of the sternocleidomastoid muscle; high level: middle point of anterior border of the sternocleidomastoid muscle) were measured by ultrasound machine and it was done after inserting laryngeal mask. Punctures of the internal jugular vein in control group were performed by traditional technique, whereas punctures in another group were performed under the way of real-time ultrasound-guided. Results ①after inserting laryngeal mask, low level: diameters of the internal jugular vein and the carotid artery do not change (p>0.05); carotid artery is pushed closer to internal jugular vein (0.39±0.53, p<0.05); partial overlap rate between them increases to 75% (60/80, p<0.05); complete overlap rate between them increases to 25% (20/80, p<0.01). middle level: diameter of the internal jugular vein becomes shorter (0.72±0.15, p<0.01), but that of the carotid artery does not change (p>0.05); complete overlap rate between them reach to 100% (80/80, p<0.01). high level: diameter of the internal jugular vein becomes shorter (0.88±0.10, p<0.05), and that of the carotid artery does not change (p>0.05); the distance between them become shorter (0.25±0.39, p<0.01); partial overlap rate between them is 30% (24/80, p>0.05); complete overlap rate between them reach to 70% (56/80, p<0.01). ②in ultrasound-guided group, 38 cases were succeeded at first attempt (95%, p<0.05), the time of cannulation last shorter [(3.4±1.3)min, p<0.05] and complication of puncture occurs lower(5%, p<0.05). whereas in control group, they are not the same ( 60%, 24/40; 7.2±3.1; 37.5%, 15/40) . Conclusion Diameter of the internal jugular vein, location of the carotid artery and the overlap between them have an obvious change after inserting laryngeal mask. At the same time, real-time ultrasound-guided technique for internal jugular vein catheterization is an more effective and safer method.