Abstract: The effects of 2，4-epibrassinosteroid（EBR）and gibberellin A3（GA3）on the growth，lipid productivity and fatty acid composition of Nannochloropsis oceanica were studied respectively. Results showed that its growth and lipid productivity were greatly enhanced with EBR of 5 and 15 mg/L，the lipid productivities increased by 7.85% and 13.97%，respectively，and the effect on total lipid content in single cell was little yet. EBR of 50 mg/L remarkably inhibited its growth. The biomass accumulation of N. oceanica was significantly improved when GA3 was each added by 5，15 and 50 mg/L in the medium. Group with 50 mg/L GA3 had the highest cell density and biomass（0.337 g/L）while its total lipid accumulation was inhibited. Overall，the lipid productivity was raised remarkably and reached 8.184 mg/（L·d）when GA3 was 15 mg/L. The proportion of saturated and monounsaturated fatty acids（16∶0，16∶1，and 18∶1）in N. oceanica decreased when adding EBR（5 and 15 mg/L）and GA3（5，15，and 50 mg/L），while the content of polyunsaturated fatty acids（18∶2，20∶4 and 20∶5）was raised significantly.

Key words: Nannochloropsis oceanica, 2, 4-epibrassinosteroid, gibberellin A3, lipid productivity, fatty acid