Abstract: On the basis of the already achieved wheat thin layer drying characteristic curve,this paper discussed wheat thin layer drying exponential model and drying constant K formula by regressive calculation, pointed out that drying process should be divided into two phases according to periods with two different K. The paper also established wheat e-quilibrium moisture content model,set concept of dynamic equilibrium content,conducted nondimensional formulae and transferring method between nondimensional and dimensional formulae, and therefore a formula of water content, drying speed and mean change affected by air condition and drying speed at different layers in wheat drying process was calculated.