Scenedesmus obliquus, inoculated in the carbonate hard water in the Yucheng County, Shangong Province, was observed to grow rapidly under the condition of supplementing certain salts and aeration.The experimental results revealed that saline-alkali waters water could be purified in some extent by the algae.After 36 houns culturing, the eliminating rates of 8 main ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, SO₄^2-, HCO₃^-, CO₃^2-) in the water respectively reached 48.5%, 5.9%, 77.5%, 74.5%, 28.2%, 46.7%, 100%, 53.1%.