Abstract: In order to achieve the maximum efficiency of rib drill pipe in construction of gas drainage holes in underground coal mines, based on the analysis of the slag drainage mechanism of rib drill pipe, numerical simulation and optimization of the structural parameters of the spiral blade of the drill pipe are carried out by using CFD technology. Theoretical analysis has indicated that the slag-off result is optimal with the rib drill pipe diametre of 98 mm, helical blade lead P of 100 mm, blade width of 16 mm. And we propose the viewpoint of changing helical blade shape to reduce slag-off resistance, when the blade outer edge fillet R is 4 mm, the slag-off resistance is reduced effectively and the whole slag-off speed is increased in the slag removal region in comparison with traditional rectangular blade.