Abstract: In order to reduce the generation of over-dried cut tobacco during the start of pneumatic drying in SH947 tower dryer, the steam flow, negative pressure in pipeline and simulated water flow under simulated running condition were analyzed and optimized by orthogonal test, and the optimized condition was verified. The results showed that:1) Simulated water flow was an extremely significant factor, steam flow and negative pressure in pipeline were significant factors affecting the generation of over-dried tobacco. 2) The amount of over-dried tobacco was reduced under the optimal simulated condition, i.e. simulated water flow 640 kg/h, steam flow 1200 kg/h and negative pressure -600 Pa.