Abstract: In order to provide more reasonable design parameters for the structural design of the offshore wind farm in Binhai, Jiangsu, the extreme wave heights obtained by different calculation methods in the project sea area are compared and analyzed by using quantitative analysis method, and the differences and effects of these methods are discussed. The results show that the extreme wave heights obtained by the annual extreme value method, the conditional extreme value method (including the storm statistics method and the upper threshold method) and the combination method are greatly affected by theoretical frequency curve, annual average frequency of tropical storms, extreme design wind speed and specific water level. Among them, the annual average frequency of tropical storms mainly affects the results calculated by the storm statistics method, with the calculated results tending to be stable and the relative deviation being less than 5% when the annual average frequency of tropical storms being not less than 1, and the extreme design wind speed and the specific water level mainly affect the results calculated by the combination method. The choice of the extreme design wind speed mainly affects the distribution of the extreme wave heights in direction and the superposition of the specific water levels mainly affects the amplitude of the extreme wave heights. At non-specific water level, the extreme wave height calculated by the storm statistics method in the conditional extreme value method is the largest, being 6.55 m, and the result calculated using the P-Ⅲ curve in the annual extreme value method is the smallest, being 5.48 m, with the relative deviation of the two being about 20%. At the specific water level, the extreme wave height calculated by the combination method along the NW—SE direction is positively correlated with the water level, that is, the extreme wave height increases when the positive water level is superimposed and decreases when the negative water level is superimposed, with the amplitude of variation being ±15%. The directional distribution of the extreme wave heights is the same as that of the extreme design wind speed. The distribution of the extreme wave heights calculated by using the design wind speeds corresponding to the extreme wave heights is more in line with actual sea conditions in all directions.