In order to investigate the current situation of benthic algal community in the intertidal zone of Sanya, field sampling was carried out including six rocky intertidal sections from Jan. 2008 to Nov. 2008. The changes of community structure and diversity of benthic algae in the intertidal zone were analyzed by species diversity indices and cluster analysis. A total of 130 species in four seasons were identified, among them, 67 species of 41 genera belong to Rhodophyta, 31 species of 16 genera belong to Phaeophyta, 29 species of 15 genera belong to Chlorophyta and 3 species of 3 genera belong to Cyanophyta. Species number altered slightly in four seasons, and its vertical distribution indicated a decreasing trend along with increased vertical gradient. Moreover, mutual species were found at mid-tide and low-tide zone, especially during the summer. Although the average biomass of benthic algae in summer and winter seemed slightly higher than that in spring and autumn, there was no significant difference between them. Dominant species of benthic algae varied with different seasons, indicating their functions in the community changed with seasons. Dominant species were Padina boryana, Ceramium japonicum, Sargassum hemiphyllum, Polyopes polyideoides in spring; Chondrophycus undulates, Sargassum cristaefolium, Amphiroa dilatata, Gelidium amansii in summer; S. cristaefolium, C. undulates, Ishige foliacea in autumn; and, Sargassum vachellianum, Symphyocladia marchantioides, Corallina officinalis, P. boryana, C. japonicum in winter. The diversity index and Margalef's species richness peaked in the winter, while the diversity index and the Pielou's evenness bottomed in the summer. The benthic algae in the intertidal zone of Sanyaare mainly composed of tropical-subtropical species, followed by warm temperate species, which generally in accordance with the taxonomic features of the Southern South China Sea. These results suggest that the community structure and diversity of benthic algae in Sanya varies with seasons despite of no significant seasonal differences in species number and biomass.