Abstract: Provided are a polymeric salt-tolerant and water-retaining fertilizer and a preparation method thereof, belonging to the technical field of fertilizers, and including the following raw materials: fertilizer, water-retaining agent and clay; the water-retaining agents includes the following raw materials: polyacrylamide, methylallyl polyoxyethylene ether, 2-acrylamide-2-methylpropanesulfonic acid, carboxymethyl cellulose, ammonium persulfate, N, N?-methylene bisacrylamide, montmorillonite and kaolin. The application also discloses the following preparation method: (1) mixing biochar and fertilizer in water to obtain a mixture A; (2) preparing soil colloid; (3) preparing a dispersion; and (4) mixing the raw materials, granulating, and drying to obtain the polymeric salt-tolerant and water-retaining fertilizer.