Abstract: The reasons causing frequent tobacco jam in feeding system of CTD(Comas Tower Dryer) were investigated by analyzing the orientation of air flow in the feeding system.Tobacco jam mainly occurred between feeding airlock and the end of expansion unit,it happened when restarting tobacco feeding after a long stoppage,the steam condensate accumulated in pipelines tended to retard tobacco's moving;or tobacco flow rate dropped abruptly,the downstream tobacco conveying belt failed to match the accelerated electronic scale,it caused tobacco piling up at the junction;during drying,violent pressure fluctuation in the system and intermittent tobacco jam resulted.The feeding system was improved by adding a drainage system,installing spike rollers on the downstream conveying belt of electronic scale and an embedded sleeve connection for pipeline joints.The results of application indicated that after improvement,the frequency of tobacco jam decreased from 2.3 to 0.2 times per batch and the standard deviation of moisture content in tobacco reduced from 3.8% to 1.7%.Tobacco moved steadily,and tobacco drying quality was improved.