As the plant areas of blueberries expand unceasingly, the realization of harvesting mechanization becomes more and more urgent. The fruit collection devices of the picking machine are designed with three-dimensional software Pro/E based on the blueberry picking machine. Meanwhile, wind sorting is used to realize the separation of fruit and leaves. In this paper, wind-sorting box is studied on the basis of the principle of wind sorting. The simulations of wind-sorting box inner are made with software FLUENT. A reliable basis is provided for the feasibility of wind sorting and a further analysis is made for the shape and the position of the inlet of wind-sorting box. And the structure of wind-sorting box is optimally designed. The improvement of the efficiency of wind sorting not only provides a theoretical basis for the separation of fruit-leaves of small berries, but also has an important meaning in agricultural machinery.