Catalytically cracking fume purifying agent

The fume purifying agent is used to eliminate SOx and NOx in catalytically cracked fume. It contains few magnesia alumina spinel and is prepared through impregnating aluminium silicate carrier in solution containing active metal component to make the carrier to carry the active metal component. It accounts for not more than 3 mass% in catalytic cracking catalyst and can eliminate SOx and NOx fromfume simultaneously and improve product distribution without affection on the quality of products. The present invention can lead to obvious environment protecting effect and economic effect.