Abstract: Halimeda is a kind of marine calcareous green algae widely growing in the tropical shallow sea of the world. It belongs to the genus of Codiaceae of Chlorophyta according to the biological classification. In addition to its important contribution to the diversity of ecosystem, Halimeda is also an important sediment producer among four major reef-building algae prevailed in various tropical marine environments. In this paper, a thorough review is devoted to the research history of Halimeda, including its depositional characteristics, its contribution to the sedimentation in tropical environment, calcification models, and the influence of ocean acidification onto the sediments. The Halimeda, as the major component of reef deposits at Shidao, the Xuande Atoll of the Xisha Islands is selected as the case of this research. Samples of different species of Halimeda are analyzed under microscope to estimate their carbonate productivity. Finally, the problems existing in the current research of Halimeda are discussed, and suggestions put forward for future researches.