Abstract: Tidal turbine blades are prone to flow separation in boundary layer under the condition of high speed or high angle of attack,which will lead to the reduction of the energy efficiency and even the stall damage of the blades. In order to solve the above problems,this paper combines the theory of Vertex Generators（VGs）with the design of turbine blades and studies the suppression mechanism of the flow separation effect on turbine blades by means of VGs. With NACA63418 airfoil design as the research object,three-dimensional models of blades with and without VGs are established,and the influence of VGs on flow separation characteristics of tidal turbine blades is studied by CFD method. The research results show that flow separation of turbine blades mainly occurs at the root part of suction surface,and the flow separation region expands radially as the flow velocity increases. VGs can effectively reduce flow separation area on the suction surface of turbine blades by suppressing the flow separation effect. In this study,compared with the turbine blades without VGs,the power efficiency coefficient of turbine blades with VGs is increased by 0.5%-5.0% and the the operation stability can be improved as well.