The invention concerns a method for obtaining an aqueous extract of Dunaliella salina microalga, in which said microalga is cultivated in the absence of light in a culture medium comprising a yeast extract, sugar and salt according to the following steps: a) solubilising a yeast extract in water； b) adding glucose to the mixture obtained in a)； c) adding Dead Sea salt； d) after total solubilisation of the salt in the mixture obtained in b), the culture medium thus obtained has a pH of between 5 and 8, and the Dunaliella salina alga is added thereto； e) moderately stirring the mixture obtained in d), in darkness and at room temperature, for a period of at least 12 hours, in order to allow the fermentation of the Dunaliella salina microalga； f) grinding and then filtering the fermented Dunaliella salina mixture obtained in e) in order to separate the soluble and insoluble materials； g) recovering a soluble aqueous raw extract to which Dead Sea salt is added； h) carrying out sterilising filtration with a porosity threshold of less than or equal to 0.2 μm； and i) obtaining a fermented aqueous extract of Dunaliella salina in which the pH is between 3.5 and 4.5. The invention also concerns an aqueous extract of Dunaliella salina likely to be obtained by the method according to the invention, a composition comprising such an extract according to the invention, and the cosmetic use of a composition according to the invention for skincare, scalp care and skin appendage care.L'invention concerne un procédé d'obtention d'un extrait aqueux d'une microalgue Dunaliella satina, dans lequel ladite microalgue est cultivée en absence de lumière dans un milieu de culture comprenant un extrait de levure, du sucre et du sel suivant les étapes selon lesquelles : a) on solubilise un extrait de levure dans de l'eau； b) on ajoute du glucose dans le mélange obtenu en a)； c) on ajoute du sel de la mer Morte； d) après totale solubilisation du sel dans le mélange obtenu en b), le milieu de cult
