Abstract: Tetraselmis is an important alga commonly used as live food in aquaculture.This paper reported the laboratory culture of its strains collected from the coasts of China, covering Guangdong, Zhejiang and Shandong Provinces.The separated strains of Tetraselmis for mono-species culture were isolated with capillary method, and their ax-enic cultures were obtained by inoculating them in plates with solid Marine Ⅲ medium (MⅢ).Modified Guil-lard & Ryther medium (MGM), M Ⅲ, and modified Marine Ⅲ medium (M Ⅲ M) were utilized for the liquid cultivation of Tetraselmis in 500 mLflasks.It was displayed that the average growth of Tetraselmis cultured in MⅢ M was the fastest at pH 7.0～8.0, and vitamin B₁₂ addition to M Ⅲ M slightly increased the relative growth rate of Tetraselmis.Therefore, the modified Marine Ⅲ medium was effective to use as a large-scale culture medium for Tetraselmis in aquaculture.