Abstract: In order to study effects of nitrogen sources and concentrations on the growth, lipid accumulation, and nutrient uptake of a freshwater microalga Ankistrodsemus sp., four nitrogen sources such as urea, ammonium chloride, sodium nitrate and sodium nitrite and different nitrogen concentrations were investigated based on 3N-BBM media.The results showed that the growth and biomass were less affected by four nitrogen sources, but it was just opposite for lipid accumulation.The highest biomass ( 2.87g /L) was obtained with urea as nitrogen source, while the optimal lipid content ( 30.17%) and lipid productivity ( 0.81g /L) was gained with sodium nitrate. Ankistrodsemus sp. was grown poorly and nearly died just on the fourth day with 0.3mmol /L sodium nitrate. Although the growth and biomass was poor with 3mmol /L sodium nitrate, the lipid content ( 37.37%) and lipid productivity ( 0.89g /L) was highest. With higher nitrogen concentration ( 9.0 ³0.0mmol /L) , Ankistrodsemus sp. was grown vigorously and had higher biomass, but the lipid content and lipid productivity were lower.So sodium nitrate was the optimal nitrogen source for growth and lipid accumulation of Ankistrodsemus sp. and the optimal concentration was 3.0mmol /L.