The invention relates to a fertilizer for saline-alkali soil. The fertilizer is prepared from the following raw materials in parts by weight: 5-20 parts of humic acid, 0.3-1 part of microorganisms, 6-16 parts of farmyard manure, 15-40 parts of straws, totally 5-10 parts of calcium superphosphate, ferrous sulfate, coal ash, furfural residues and flue gas desulfurization gypsum, 6-14 parts of a nitrogen fertilizer, 2-4 parts of a phosphatic fertilizer and 2-3 parts of a potassic fertilizer. The invention further relates to a preparation method of the fertilizer for saline-alkali soil. The fertilizer for saline-alkali soil, which is provided by the invention, has the beneficial effects that the fertilizer for saline-alkali soil has the characteristics of being low in cost and simple in preparation method, can be used for effectively improving the condition of saline-alkali soil, reducing the content of salt of soil and the pH value and increasing the content of organic matters in soil, and is particularly suitable for being applied to the saline-alkali soil.