Due to its special structure of deep draft cylinder hull piercing into the water, the Spar platform is easily subjected to vortex-induced motions in certain flow conditions. In order to study the influences of different helical strakes thicknesses on the vortex-induced loads of Spar platform of floating wind turbine, based on the CFD method, the numerical analysis was carried out for the Spar platform with different thicknesses of helical strakes, the flow field parameters including vortex field, pressure field and lift and drag coefficient were analyzed in detail. The results showed that, the helical strakes was effective in restraining the vortex-induced loads, and the amplitude of the lift coefficient increased first and then decreased, the drag coefficients decreased gradually with the increment of thickness. In the research range, the lift coefficient was minimum when the thickness was 0.10D, while the drag coefficient varied little from bare platform,which had the best suppression effects on vortex-induced loads.