The invention discloses a saline-alkali land soil conditioner and a preparation method thereof. The saline-alkali land soil conditioner is prepared by adding water in citric acid, polymaleic acid-acrylic acid copolymer, sodium polycrylate and fatty alcohol-polyoxyethylene ether. The preparation method comprises the following steps: weighing raw materials in weight proportioning; adding partial water in a reaction kettle for heating to 50-60 DEG C; adding the fatty alcohol-polyoxyethylene ether, the polymaleic acid-acrylic acid copolymer, the sodium polycrylate and the citric acid in the reaction kettle in turn for fully dissolving; subsequently, adding rest water in the reaction kettle and cooling to 20 DEG C; and after sampling and qualified inspection, measuring and packaging to form a finished product. By using the conditioner, the physical and chemical properties of the saline-alkali soil are obviously improved, heavy metal ions are complexed, emulsification and oil removal are achieved, salinity infiltration is accelerated, alkaline of soil is neutralized, and the pH value is regulated; and the desalination amount of the conditioner can reach above 50%, and the conditioner has the advantages of short improvement period, durable management effect and universality, saves water, increases benefits, yield and income and is environment-friendly.