The invention belongs to the field of soil amendments, and particularly relates to an alkaline soil amendment. The alkaline soil amendment is prepared from polyglutamic acid, activated humic acid, amino acid waste liquid, ammonium polyphosphate, citric acid fermentation waste residues, Pullulan polysaccharide, polyaspartic acid, sodium carboxymethyl starch, tetrahydropyrimidine and trehalose. Accordingly, the purpose of improving alkaline soil is achieved by adding a water retaining agent to control salt, adding acidic organic matter to activate humic acid, adding the amino acid waste liquid to control the pH value, adding a chelating agent to prevent solidification and adding an osmotic pressure stabilizer to prevent root dehydration. The amendment has the advantages that raw materials are natural, non-toxic and biodegradable, the cost is low, the yield is high, and the effectiveness of soil nutrients can be fully achieved; the activated humic acid improving the reactivity of organicmatter and the amino acid waste liquid mainly consisting aginomoto waste liquid are synergized; the water retaining agent, the chelating agent and the osmotic pressure stabilizer act together, and theadvantages of the amendment are strengthened.