The invention relates to an alkaline soil restoration material and a preparation method thereof. The alkaline soil restoration material is composed of urea-modified polytrimethylene carbonate, phosphoric acid-modified polytrimethylene carbonate and phosphoric acid-modified polyacrylamide, and the urea-modified polytrimethylene carbonate is modified by acid Polytrimethylene carbonate, urea, ammonia water, ethanol and amino acid reaction are prepared, and described acid-modified polytrimethylene carbonate is made of polytrimethylene carbonate, phosphoric acid, urea, oxalic acid, water, A-171 silane Coupling agent, Sr-10 emulsifier, N,N-dimethylformamide and ethanol reaction are prepared, and described phosphoric acid modified polytrimethylene carbonate is made of polytrimethylene carbonate, urea, ammonium sulfate, phosphoric acid It is prepared by reacting with toluene, and the phosphoric acid-modified polyacrylamide is prepared by reacting polyacrylamide, phosphoric acid, oxalic acid, concentrated sulfuric acid and N,N-dimethylformamide. The alkaline soil remediation material provided by the invention has excellent properties of adjusting soil acidity and alkalinity.