Abstract: The effect of different organic sources and the best concentration of organic source for growth rate, total lipid content and photosynthesis of Monoraphidium sp.cells were investigated.Results showed that the addition of glucose and sucrose could promote the growth rate, total lipid content and photosynthesis of Monoraphidium sp.cells, the addition of glycine could promote the growth rate of Monoraphidium sp.cells, but cut down the total lipid content.Besides, the cell growth was obstructed when sodium acetate was added in.It indicated that Monoraphidium sp.cells had the ability of utilizing the organic carbon sources to grow mixotrophically.In BG-11 medium with glucose concentration of 5g/L, the dry weight, total lipid productivities and photosynthesis of Monoraphidium sp.were 7.8, 3.2g/L and 240.3umolO2· (mg·chla) -1·h-1, respectively, which were 5.6, 8.0, 1.3 folds of that obtained under autophototrophic condition.The best concentration of organic source for growth rate and total lipid content of Monoraphidium sp.cells was 10g/L.