Abstract: Granular flow lubrication is an efficient and green solid lubrication technology, which has been initially applied in the field of mechanical cutting. However, for semi-closed processing such as drilling, effectively promoting the particle lubrication medium to enter the cutting zone through the narrow gap between the bit and the hole wall is the premise and guarantee of reliable lubrication. In order to explore the flow characteristics of granular medium in the gap between drill and hole wall and promote its effective introduction, the discrete phase model in Fluent software was used to conduct numerical simulation of particle lubrication medium introduction.The gap between drill pipe and hole wall and the particle concentration of inner hole wall are compared by simulation calculation under different particle medium and drilling parameters. The results show that the material of solid particles is an important factor affecting the import amount. The concentration of MoS₂ in the gap between drill pipe and hole wall is higher than that of graphite, and the adhesion amount of hole wall is also larger.The increase of tool speed and feed speed is conducive to the introduction of lubricating particles, and the effect of speed is more obvious. This research has certain practical value in improving the lubrication effect of particles media and promoting the application of this technology in the drilling of difficult-to-cutting materials.