Abstract: In mixed-flow grain dryer, there is uneven drying because the air distribution is not uniform a-long the longitudinal direction of air ducts. In this paper, the characteristic of the air distribution is investigated by experiments. It is also found that conical air duct is not as effective as expected in improving air distribution uniformity. A new type of air duct with changed perforation rate plate is designed, which can eliminate the unevenness of air flow at the expense of 3～4 mm water column increase in air resistance.