The invention discloses a treatment method for sodium sulfate salt lake water for dunaliella salina cultivation. The treatment method comprises the following steps: 1) pumping sodium sulfate salt lake water into a mirabilite frozing tank, separating and depositing mirabilite in the lake water to the bottom of the mirabilite frozing tank by utilizing a natural environment at minus 10 DEG C, leading brine on an upper layer into a brine storage tank, and evaporating till 18-22 baume degrees; 2) when the daily mean water temperature of the brine storage tank is greater than 10 DEG C, leading the brine in the brine storage tank into a dunaliella salina cultivation tank till the depth of the brine is 30-40cm, performing natural evaporation, increasing the salt degree of the brine to 25-26 baume degrees, discharging out brine which is 5-10cm deep from the upper surface of the brine, and adding water into the residual brine till the salt degree is 22-24 baume degrees, thereby obtaining brine applicable to cultivation of dunaliella salina. A product prepared by using the method is applicable to dunaliella salina cultivation, sodium sulfate type salt lakes can be utilized, and the dunaliella salina cultivation cost can be lowered.