The island is greatly affected by the sea breeze, hence its wind field characteristics are constantly changing. Accurate understanding of its wind characteristics is the basis of wind resistance design for related construction. However, the existing mathematical models describing the characteristics of wind field are usually only suitable for inland flat terrain, which is not enough to describe the wind environment similar to island terrain. Therefore, the wind tunnel test method is used to study the wind field characteristics in a valley on Nan'ao Island. The results show that: The closer to the center of the valley, the greater the variation of mean wind speed profile and turbulence intensity profile; The results show that the power spectrum of fluctuating wind speed at each measuring point under the main wind direction is in good agreement with the von Karman spectrum. The research results can provide experimental basis for similar engineering design.