The evaporation region medel,based on the characteristic of the moisture evaploration inside a capillary tube and the pore distribution,is presented for analyzing the moisture evaporation inside the porous capillary material in the decraseing rate period of drying. The differential equation describing the moisture evaporation region is established and the general expression calculating the evaporation intersity is obtained, Then,the influences of the pore distribution on the evaporation region and the evaporation intensity are alse discussed.