The RNG k-ε turbulence model was used for numerical simulation of the three-dimensional flow process of water flows around the spur dike，so as to analyze the influence that different lengths of bend head have on the structure and velocity field of water flows around the spur dike.The computed results show that transverse vortex appears at the bend head section under the influence of the bend head；The longitudinal flow velocity decreases in the area away from the dike head；High flow velocity concentrates towards the dike head；Transverse flows weaken behind the dike axis；The maximum difference between upstream and downstream water levels reduces；And the effect of influence enhances as the length of bend head increases.These findings lay a foundation for investigation on improving the navigation flow condition around the spur dike by the bend head.