Tower vacuum dryer room is the key device for continuous vacuum dryer. In order to lower the cost of manufacture, the wall of dryer should be thinner. But as the pressure container, it must have the well intensity while operating. Because its complex structure, the simple calculation is not enough, the finite element analysis in intensity control was carried out. The model of vacuum dryer was built, the intensity of general primary membrane stress and the intensity of primary bending stress was picked-up on the max stress intensity point through the path of wall thickness. Accord with JB4732-1995, the structural strength was fulfilled the requirement.