The invention provides a method for preparing alpha-ketophenylalanine calcium. The method includes carrying out organic alkali and organic alcohol catalytic cyclization reaction on hydantoin and benzaldehyde by the aid of glycine, strong alkali and organic alcohol obtain benzalhydantoin; carrying out ring-opening hydrolysis reaction on the benzalhydantoin in sodium hydroxide alkali liquor to obtain alpha-keto-beta-methyl sodium valerate and carrying out filter-press by the aid of novel partition plate and membrane filter presses to obtain high-purity alpha-keto-beta-methyl sodium valerate; carrying out reaction on the high-purity alpha-keto-beta-methyl sodium valerate and calcium acetate with the equal proportion to obtain the alpha-ketophenylalanine calcium. The glycine, the strong alkali and the organic alcohol are used as catalysts, and the hydantoin and the benzaldehyde are used as raw materials. The method has the advantages that the common organic alkali and organic alcohol catalytic cyclization reaction is carried out to prepare alpha-ketophenylalanine calcium products, the products are high in purity, the molar yield can reach 99%, organic alkali and the organic alcohol can be recycled by 10 batches, and wastewater can be prevented.