The invention discloses a microalgae nutrition repair liquid for relieving grassland desertification, which comprises a microalgae mixed liquid, the microalgae mixed liquid comprises seven active microalgae, and the added microalgae comprises the following components in parts by weight: 5-40 parts of hylothrix tadeeri, 5-40 parts of hylothrix wonderi, 10-50 parts of microcoleus vaginalis, 5-40 parts of pseudocladoidea, 10-50 parts of monofidus microfidus and 30-80 parts of chlorella pyrenoidosa, and the microalgae mixed liquid comprises the following components in parts by weight: 5-40 parts of hylothrix tadeeri, 5-40 parts of hylothrix wonderi, 10-50 parts of microcoleus vaginalis and 30-80 parts of chlorella pyrenoidosa. In addition, 10-50 parts of nitrogen-fixing anabaena or 20 parts of cotton algae are selected to be added. Aiming at the grassland desertification region, the nutrient restoration liquid can restore soil, supplement natural nitrogen, activate soil trace elements, improve plant stress resistance and prevent plant diseases and insect pests, the seven microalgae have good compatibility, the number of microalgae active cells in each 1mL of the nutrient restoration liquid can reach more than 106, and the nutrient restoration liquid has good application prospects. The storage life of the nutrient repair liquid reaches 18 months, the culture process is obtained through a large number of experiments, and the culture efficiency is high.