Abstract: Effect of attapulgite on PM_2.5 emissions and agglomeration during coal combustion was investigated in a fixed bed system. The effects of addition amount, combustion temperature, mole ratio of calcium to sulfate and combustion atmosphere on mass and number concentration and collection efficiency of PM_2.5 were analyzed. The results show that attapulgite added during coal combustion can effectively reduce PM_2.5 emissions. The suitable amount of attapulgite is no more than 3%. PM_2.5 emission during coal combustion in air is higher than that in O₂/CO₂ atmosphere. PM₁ mass concentration decreases with increasing mole ratio of calcium to sulfate, while PM_1~2.5 mass concentration increases, indicating an increasing trend in particle size. Increasing combustion temperature will increase PM_2.5 emission and reduce its collection.