Abstract: The macro site selection of offshore wind farms, as a preliminary project for offshore wind power construction, plays a crucial role in the success or failure of wind farm construction and its future benefits. This article is based on Mamdani type fuzzy inference to obtain the comprehensive evaluation value of the criterion layer, and to obtain the optimal site and ranking of the advantages and disadvantages of alternative sites. Adopting the "If Then" inference rule to avoid complex mathematical formula derivation, and introducing language variables and membership functions, the uncertainty of the decision-making process is well reflected. The use of Matlab toolbox enhances the decision-making process of dynamic interaction between experts and computers, making the evaluation process more convenient and efficient, and improving the reliability and applicability of site selection.