Abstract: In this paper, the observered data of low-layer wind and temperature collected from western outskirts of Haikou, Hainan, are analysed. Mean boundary layer structure, generation and development of ground-level inversion and inner boundary layer on the coastal area of interest, which is in China's northern tropical area, are analysed. It is found that inner boundary layer can be produced under intensive sunshine in dry or rainy seasons, and the mixing layer on the coast is obviously deeper than that of inland.