This paper does researches for vertical axis tidal turbine based on academic analysis and numerical simulation. Keep on the tip speed ratio and change the inlet speed. And then analyze hydraulic performance of the different tidal turbines. For the problem in the tidal technology, use airfoil cross-section that is suitable for low speed flow use, change the structure of the impeller blade design, and combined with numerical simulations, so as to increase the vertical axis tidal turbine hydraulic characteristics and operating reliability.