In China, the tower vacuum dryer has been studied and developed for a number of years. These studies have highlighted its important advantages in energy, quality and efficiency of drying process. The granular flowing characteristic has been studied in 2D method. But the 3D simulation method has not been given. Conditions to avoid blocking of the material within the inner portion of the dryer were re-determined. The retention time of the granular material was studied and a mixture characteristic across the dryer was re-determined. The simulation results makes the results of past more be creditable.