Abstract: Secondary circulation in the spirals is a key flow feature that promotes the formation of the various mineral belts and then realizes the particles separation.Therefore, an in-depth study of the distribution characteristics of the secondary circulation is beneficial to reveal its separation mechanism.In this paper, the influence of different numerical conditions on the radial velocity distribution in the spirals is investigated base the CFD method in order to determine a suitable calculation method for water flow characteristics in the spirals.Furthermore, the spatial distribution characteristics of the secondary circulation in the spirals are investigated.The results show that the more stable CFD simulation results are more accordant to the theoretical distribution characteristics of radial velocity can be obtained by the turbulence model of RNG k-ε, the mesh number of 522 410 and bottom mesh size of 2 mm.With the increase of turns as well as the primary velocity, the centrifugal inertial force on the fluid is strengthened, and the secondary circulation starts to form and stabilizes gradually.Meanwhile, the depth position of the critical point of radial velocity moves downward, where the direction of the flow velocity achieves transition and the radial velocity is zero.The flow ratio of the upper flow and the lower flow is changed, and the distribution characteristics of the upper fluid along the water depth become more stable.After the formation of the secondary circulation in spirals, the depth position of the radial velocity critical point gradually moves down with the fluid particle moving outward, and the pattern of the secondary circulation profile along the groove surface is thin inside and thick outside.The maximum outward velocity of the surface fluid and the maximum inward velocity of lower fluid both appears at the position approximately 10 mm from the endpoint of the outer edge of the spirals.The research results can provide the references for the further study of solid particles motion and separation behaviors in the flow field of spirals.