Vertical Axis Tidal (VAT) turbines are used as ocean-powered devices to generate electricity from movements in ocean as a renewable source of energy. In this research, a number of CFD simulations have been carried out using the mixed-level modified Taguchi technique to determine the optimal hydrodynamic performance of a VAT turbine. The influence of four parameters: twist angle, camber position, maximum camber, and chord/radius ratio has been studied. The interaction of these parameters is investigated using the Variance of Analysis (ANOVA) approach. The Taguchi analysis showed that the most significant parameter affecting hydrodynamic performance of the turbine is the twist angle and the least effective parameter is chord/radius ratio. The ANOVA interaction analysis showed that the twist angle, camber position and maximum camber have significant interaction with each other. The results showed that the power coefficient (Cp) for the optimized VAT turbine is improved by 24% compared to the baseline design. Analysis of the pressure coefficient (Qp) indicates that the hydrodynamic performance of VAT turbine is sensitive to cambered blade. Moreover, the flow separation in the optimized model is greatly reduced in comparison with the baseline model, signifying that the twisted and cambered blade could be effective in normalizing the spraying vortices over blades due to suppressing dynamic-stall. The findings of this research can provide guidelines for optimization of vertical turbines.