This study of the effects of culture conditions (season, salinity, growth period, culture medium ) on lipid and fatty acid composition of Isochrysis galbana 3011 showed: (1) Total lipid and DHA contents in the algae increased with decreasing temperature; (2)Too high and too low salinity slowed production of total lipid and DHA, suitable salinity was 2.5%-3.0%; (3) Total lipid and DHA contents in the exponential growth period were much higher than that in the static period; (4) Total lipid and DHA content of the algae growing in different culture medium varied very much, and the optimal medium for growth of the algae was:N, 2.0 mmol/L; P, 0.05mmol/L: Fe, 0.002 mmol/L; Si, 0 mmol/L; and C, 0 mmol/L.