The invention relates to a culture method of Dunaliella and application of Dunaliella in biomass energy, which relate to the Dunaliella. The invention provides a culture method of Dunaliella which is simple and economical, not only can be used as the biomass energy, but also can efficiently capture and store carbon dioxide, and the application of the Dunaliella in the biomass energy. The culture method is characterized by filtering in sea water; inoculating the dunaliella seed in sea water culture base, culturing the seed for 14 to 35 days, mixing continuously every day, culturing the dunaliella for a year, and harvesting the dunaliella cell when density of the dunaliella reaches 104 to 106 per ml. The dunaliella is used as a material of the biomass energy, high-concentration sea water isused as culture base, and the carbon dioxide is assimilated through the growth of the dunaliella so as to accumulate the biomass energy materials such as grease, starch and the like.