Abstract: This reasearch solves the uniformity of the airflow through orifices in the inlet and outlet ducts of the wood drying compulsory centralize air-exchange device . The optimal diameters and distribution of the orifices were obtained by examining the air flux and velocity at the inlet and outlet ducts using the combination of the theoretical analysis and numerical simulation（CFD）. The results indicated that the difference of air flux in the inlet orifices was less than 5.1%, while the difference of air flux in the outlet orifices was less than 7.3%. Since both of the differences were less than 10%, it was ensured that the uniform airflow distributions in the inlet and outlet orifices were achieved. In addition, the orifice radius distributions from the end to the beginning of the inlet and outlet ducts were examined. Two quadratic distribution curves of the orifice radius for the air inlet and outlet ducts were developed.