Calcium carbide slag is a kind of waste residue with calcium dihydroxide as the main component after acetylene gas is obtained by hydrolysis of calcium carbide.In this paper,the characteristics of calcium carbide slag and the problems of fine particle size (about 80% particle size in 10~50  μm),high calcium content ［Ca(OH)2 content ≥90%］,high moisture content (about 35%) and high harmful composition of calcium carbide slag are studied,and a series of experimental studies were carried out.The experimental results show that the calcined CaO has high activity and can be used as raw material for calcium carbide production.However,due to its high impurity content,it is necessary to use CaO in combination with the calcined active lime of natural limestone to reduce the influence of harmful components on calcium carbide furnace,the proportion of the mixture can reach about 20%.Based on the characteristics of calcium carbide slag and the experimental results,a complete technical route (suspension calcination) for the preparation of active calcium oxide from calcium carbide slag is proposed.