In the process of designing mechanical rope-arranging device, there are two outstanding problems. First, in order to ensure the rope next to roller shutter to change layers accurately, the transition circular groove with appropriate length should be designed on the end of double helix axis; then the moving distances of a turning circle of the roller rope-arranging device should match with the ropes of different diameters. To solve these problems, equations were established based on the common influencing factors of pitch and transmission ratio for accurate calculation. It is proved by the field testing that the rope-arranging device designed on the basis of the calculation results is practical and reliable.