In view of the loess formation, reverse circulation air-jet-cutting technique was proposed with air instead of drilling fluid. The bit structure parameters were optimized by Fluent software, the parameters of different diameters of bottom jet orifices, the number of bottom jet orifices, the diameters of bottom jet orifice enlarged sections, the number of bottom jet orifice enlarged sections and the number of bottom jet orifices were stimulation analyzed. The results show that in the case of a certain inlet air flow, air-jet-cutting and reverse circulation capacity of the drill bit would be weakened while increasing the diameter and number of bottom jet orifices. The best performance of air-jet-cutting and reverse circulation capacity can be achieved by the design structure with 2 bottom jet orifices of 3mm in diameter, the bottom jet orifice enlarged section of 8mm and 5mm in the diameter and the length respectively and 5 internal jet orifices.