The Core business in distribution center is to sort orders, the efficiency of sorting will directly impact on the whole logistics distribution center. Random automatic sorting of unit material is a control method by commonly used, this article based on the actual demand for order picking under herein scale, put forward polling control as a innovative idea to sort unit of materials, and divide the sorting order of unit materials into large flow order picking and general picking, using the full service mechanism to control the order picking for the large flow, and using parallel door service limit mechanism to control the order picking for ordinary flow, thus establish the automated sorting facility model of completely - parallel threshold polling portfolio for entire polling sorting system, solve the related performance parameters, and then compare the cost of unit materials which are sorting by fully automatic random sorting line and a combination of automatic polling of completely - parallel threshold, give out the specific formula to calculate their cost of corresponding points, sorting efficiency and time, and combined with practical, make out numerical calculation and analysis.