A large eddy simulation method are used to study the flow field of the naca66 (mod) hydrofoil in this paper. The Reynolds number of hydrofoil chord length is 1.5 × 105, and relatively detailed flow field data are obtained. Different Liutex vortex identification methods are used to analyze typical tip vortices and random vortices. Firstly, Liutex and Omea_Liutex methods are used to identify the vortex. When the design attack angle of hydrofoil is 0° and the value of Omea_Liutex is 0.53, a cleaner tip vortex can be obtained. Then, the flow field of hydrofoil with different attack angles and different skew parameters is analyzed. The attack angles of the hydrofoil are −4°, -2°, 0°, 2°, and 4° respectively. When the angle of attack is negative, the tip vortices of the hydrofoil are not obvious, mainly the vortex structure at the trailing edge. In this case, the difference between Liutex vortex identification method and vorticity identification method is not obvious. At the positive angle of attack, the tip vortices identified by Liutex method are more pure, while the tip vortices obtained by the vorticity identification method are bound to the shear vortices on the surface of the hydrofoil, and can’t distinguish the tip vortices boundary well. Tip vortices recognized by Liutex develop farther downstream with the current, and the larger the angle of attack, the more obvious. The skew parameters of hydrofoil are −12°, −6°, 0°, 6° and 12°. The tip vortices of hydrofoil do not change significantly with the skew angle changing from negative to positive. Liutex method can still identify tip vortices well. At the negative side bevel, the vorticity method identifies more shear vortices on the suction side, while the vortices obtained by the Liutex method are more inclined to rotating vortices, and the vortices are more pure in structure. While at the positive skew angle, such as at the 12° skew angle, the complete trailing edge vortices are more concentrated and the structure is clearer.