Abstract: Dome seeing is generated from turbulent fluctuation around the telescope caused by a telescope enclosure. It is one of the main factors affecting the image quality and really a waste for excellent site condition.Dome venting is an essential part in dome design. It could promote the air circulation and reduce the dome seeing effect. Due to the dome seeing issue of Xinglong 2.16-m telescope, this paper describes the design of hoist-duct venting system and the analysis of venting results with computational fluid dynamic software. It's shown that the hoist-ductventing system could improve the heat balance rate and make the air more stable. The results of dome venting give a suggestion of venting strategy and provide reference for hoist-ductventing update of 2.16-m telescope to improve the image quality and efficiency.