The work aims to study the flow field characteristics of bulk grain swirl conveying to provide basis for efficient bulk grain conveying. First, the strength of the swirl field was revealed by the swirl intensity, the definition and calculation formula were given, and the dispersion and realization of swirl intensity were discussed. Based on the swirl intensity, the characteristics of swirl field generated by spiral vane spin-off device were studied. According to the Realizable k-ε turbulence model, the calculation was completed through numerical simulation with CFD-DEM coupling. Bulk grain particles entered the pipeline at a certain inlet velocity and began to spiral under the guidance of the swirl device on the vane, and the axial velocity of grain particles was distributed symmetrically along the radial direction. Tangential velocity was distributed symmetrically along the pipe axis. In conclusion, through a comparative analysis of the swirling parameters, the optimal boundary conditions for the swirl field are determined. At an inlet axial velocity of 20 m/s and a blade count of 6, the swirl effectively induces sufficient rotation in the grain particles, preventing sedimentation and achieving the best transport conditions.