effective ways to achieve its efficient use, but the complex composition and high silicon content of calcium carbide slag restrict the productquality of the preparation of activated calcium oxide. Based on the distribution law and occurrence form of silica impurities in calcium carbide slag, the effect of flotation agents on the removal of silicon in calcium carbide slag were systematically investigated, a suitable desilication reagent for calcium carbide slag was obtained, the changes in elemental composition of calcium carbide slag and the changes in theproperties of active calcium oxide products after roasting before and after flotation were studied, and a process route for the preparationof calcium oxide by flotation desilication coupled with roasting of calcium carbide slag was put forward. The results indicate that calciumhydroxide is the main component of calcium carbide slag, which also contains some silicon impurities such as silica and aluminosilicate.Through a reverse flotation desilication test combined with sodium hexametaphosphate of 400 g/ t and dodecylamine of 125 g/ t, the silica mass fraction of calcium carbide slag is reduced from 3.14% to 2.85%, and the calcium recovery rate reaches 87.9%. The calcium carbide slag after flotation separation of silica impurities could be completely converted into calcium oxide after roasting at 900 ℃ , andthe calcium oxide mass fraction in the product is 94.46%, the compressive strength is increased from 3.17 MPa to 3.87 MPa, and the metallurgical activity is increased from 341.6 mL to 385.5 mL, and the product performance is improved. The above research can provide reference for the recycling of calcium carbide slag.