The thermal stability, particle size and morphology and oil absorption of aluminum hydroxide(ATH) treated by drymodification with three different modifiers were investigated. The experimental results show that the thermal stability of ATHpowder is markedly improved by dry modification technology with the following modifiers such as phosphoric acid, polyacrylic acidand the mixture of phosphoric acid and polyacrylic acid. The best effect comes from pure phosphoric acid, and the initial temperaturefor the loss of crystal water of ATH powder modified with pure polyacrylic acid can reach about 202 ℃ that is approximately 10 ℃higher than that of ATH powder before modification. The phenomena of agglomeration and macro-aggregate badly exist in ATHpowder modified with the modifiers containing phosphoric acid. The growth of particles and agglomerations of powders are notevident in ATH powder modified with pure polyacrylic acid. The oil absorption of ATH powder modified with the modifierscontaining phosphoric acid is apparently larger than that of original ATH powder and ATH powder modified with pure polyacrylicacid. The oil absorption of the ATH powder modified with pure polyacrylic acid is slightly smaller than that of original ATH powder. The thermal stability, particle size and morphology and oil absorption of aluminum hydroxide (ATH) treated by dry modification with three different modifiers were investigated. The experimental results show that the thermal stability of ATHpowder is markedly improved by dry modification technology with the following modifiers such as phosphoric acid, polyacrylic acid and the mixture of phosphoric acid and polyacrylic acid. The best effect comes from pure phosphoric acid, and the initial temperature for the loss of crystal water of ATH powder modified with pure polyacrylic acid can reach about 10 ° C higher than that of ATH powder before modification. The phenomena of agglomeration and macro-aggregate badly exist in ATHpowder modified with the modifiers containing phosphoric acid. The growth of particles and agglomerations of powders are notevident in ATH powder modified with pure polyacrylic acid. The oil absorption of ATH powder modified with the modifierscont aining phosphoric acid is apparently larger than that of original ATH powder and ATH powder modified with pure polyacrylic acid. The oil absorption of the ATH powder modified with pure polyacrylic acid is slightly smaller than that of original ATH powder.