The invention discloses an amendment for alkaline-saline soil. The amendment contains the following raw materials: furnace slag, straw powder, an organic fertilizer, tetracycline bacterium residue, ferrous sulfate, a compounded fertilizer, KL biological bacteria and clay. A preparation method for the amendment comprises the following steps of carrying out air-drying on the straw powder, the furnace slag and the organic fertilizer, carrying out high-temperature composting fermentation on the tetracycline bacterium residue, crushing straws, the organic fertilizer, the furnace slag and the tetracycline bacterium residue firstly with a crusher, then, uniformly mixing the crushed straws, the crushed organic fertilizer, the crushed furnace slag and the crushed tetracycline bacterium residue according to a production proportioning ratio, then, loading the mixture to a paired-roller extrusion type granulator for extrusion forming with the help of the clay, enabling granules to pass through a magnetizer and then pass through a dryer, then, inoculating the KL biological bacteria to the granules, then, enabling the granules to pass through a mesh screen, bagging the granules, and encapsulating bags, thereby preparing the amendment. A use method for the amendment is simple and convenient, the product of the preparation method is used before crops are sown, the desalination effect is obvious, the influence on the seedling emergence of the crops caused by salt damage can be obviously lowered, and the rate of seedling emergence is increased. After the product of the preparation method is used, the soil can be amended, and the product can be absorbed and utilized by the crops, so that the amendment plays an obvious role in inhibiting salt and increasing yield.