The invention belongs to the field of metal material, which is a calcium remover for aluminum-silicon alloy and a preparation method thereof. The calcium remover comprises aluminum and fluorine; the calcium remover is characterized by further comprising nickel, silicon, boron and carbon, the mass percentage of each element is as follows: 11.0-21.0% of the aluminum, 24.0-44.0% of the fluorine, 5.0-30.0% of the nickel, 7.0-35.0% of the silicon, 0.1-5.0% of the boron and 5.0-20.0% of the carbon. The preparation method comprises the following steps: weighing each material according to the mass percentage, 35-65% of AlF3, 20-50% of master alloy Ni-Si-B and 5-20% of carbon powder; performing rapid solidification processing of argon aerosol to the master alloy Ni-Si-B, obtaining granular master alloy Ni-Si-B; uniformly mixing the AlF3 powder, the granular Ni-Si-B powder and the carbon powder, using a briquetting machine to press the powder, and preparing into lumpish calcium remover. The calcium remover for the aluminum-silicon alloy of the invention is highly efficient and environmentally friendly, simple in preparation process, good in process stability, low in cost and the like; when the adding amount is 0.2%, the calcium content in the industrial aluminum-silicon piston alloy is reduced lower than 20 ppm, and the calcium remover for the aluminum-silicon alloy is a novel modification agent similar to eutectic Al-Si alloy.