Abstract： LES model was conducted in the analysis of hydrofoil tip vortex flow field．In order to reduce the discrete error induced by the grid, mesh refinement was applied to the area of the tip vortex core in numerical simulation. The axis velocity and tangential velocity of the tip vortex flow field with no cavitation were calculated and the results are in good agreement with experiments. The scaling law of tip vortex cavitation inception number is introduced and has been modified with the data of vortex core radius and vortex strength.