Wind energy, as one of the most accessible green energy sources, not only contributes significantly to carbon neutrality and emission reduction, but also has along-term impact on China's energy use. To capture wind energy, neither horizontal axis wind turbine (HAWT) nor vertical axis wind turbine (VAWT) can avoid excessive bearing load and unstable performance. The fast increase of vertical load prevents the development of large size wind turbine, especially for VAWT. Given that, a new floating VAWT has been developed, which utilize the buoyant force of liquid to carry the vertical load instead of the bearing to overcome the problem. However, the performance and critical control, design, and optimization parameters of this floating VAWT remain unclear. In this study, numerical simulations using computational fluid dynamics were performed to evaluate the performance of the floating VAWT, with an emphasis on the effect of blade shape (NACA 0018, S-1046, DU 06-W-200, NACA4425, and EN0005) and its associated moment, offset pitch angles (-8° to 4°), and blade numbers (3 and 5) on the power coefficient and self-starting performance. A wind-induced rotation governing equation based on aerodynamic torque was derived and applied via user-defined function programming. In comparison to other blade shapes, the turbine with the S-1046 demonstrated superior performance in terms of self-starting, power coefficient, and fatigue characteristics. The mean power coefficients of both 3- and 5-blade turbines were increased when a negative offset pitch angle was applied and reached their maximum values when the offset pitch angle B=-4°. In terms of the blade number, the 5-bladeturbine had a higher mean power coefficient than the 3-blade turbine at low wind velocities (U<6m/s), while it became opposite at high wind velocities (U.>9m/s). The analysis of the turbine's flow field revealed that offsetting the pitching angle and blade number could suppress or delay vortex separation, thereby improving the performance. Based on our simulation, a hybrid VAWT was proposed to optimize the performance of floating VAWT. With this combination, the downwind vortex shedding was suppressed, thus improving the overall performance. The findings of this study not only provide insight into the design and optimization of this floating VAWT, but also serve as methodological reference for other turbines simulation. Key words: Vertical axis wind turbine, Simulation, Blade shape, Offsetting pitch angle, Mean Power coefficient