Abstract. The thesis focuses on how to get the mathematical model of mass transfer under some certain simplified conditions and how to gain the moisture content of materials under drying. In this process, authors utilized phenomenological equations of heat and moisture transfer and analyzed the relationship and cross effects between force and flow, which were about various kinds of heat and mass transfer. In addition, the authors also used computer simulation in drying process. The result of the study is that drying rate depends on the speed of the internal moisture migration. The conclusions of this thesis have great significance for selecting the dryer and in the actual production.