As the main condition of good wood drying is the uniformity of air velocity on the pieces, we focus in this paper on the problem of air flow in a wood drier loaded with stacks of planks. The case of the upper ventilation is mainly considerad A numerical study, based on the. resolution of movement equations for a turbulent flow, concerns the inlet and outer part of the stack. The result helped us to understand the part played by the space on each side of the stack, which differs for large or narrow distances from the wall. An experimental study gave us values for velocity distribution in the stack for given geometrical ratio of the drier and led us to recommend some rules for good loading.