Abstract:KH560 was applied as modifier to prepare anti-hygroscopic calcined dolomite. The optimum condition for modification and modified mechanism were studied. The results show that calcined dolomite contact angle expands from 37.04° to 100.05°, and moisture absorption rate within 700 min drops from 2.0% to 0.35% with 82.5% reduction under the optimum conditions including KH560 dosage of 0.025 mL for one gram calcined dolomite, modification temperature of 50 ℃, and modification time of 8h.