Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains, namely, Isochrysis galbana and Nannochloropsis sp., through CO2 enrichment cultivation were investigated in this study. The optimum culture conditions of the two microalgal strains are 10% CO2 and f medium. The maximum biomass productivity, total lipid content, maximum lipid productivity, carbon content, and CO2 fixation ability of the two microalgal strains were obtained. The corresponding parameters of the two strains were as follows: ((142.42 +/- 4.58) g/(m(2)center dot d), (149.92 +/- 1.80) g/(m(2)center dot d)), ((39.95 +/- 0.77)%, (37.91 +/- 0.58)%), ((84.47 +/- 1.56) g/(m(2)center dot d), (89.90 +/- 1.98) g/(m(2)center dot d)), ((45.98 +/- 1.75)%, (46.88 +/- 2.01)%), and ((33.74 +/- 1.65) g/(m(2)center dot d), (34.08 +/- 1.32) g/(m(2)center dot d)). Results indicated that the two marine microalgal strains with high CO2 fixation ability are potential strains for marine biodiesel development coupled with CO2 emission reduction.