Abstract: Changing the silica gel pore structure with bimodal pore radius distributionby using ammonia or ammonium salt, the macroporous silica gel products with bimodal pore radius distribution can be gained. Whether to adding ammonia or ammonium salt or not, the amount of ammonia or ammonium salt, different adding time and reaction temperature to affect silica gel performance were investigated in this paper. The results showed that when adding ammonia or ammonium salt to the solution in the initial stage, ammonia or ammonium salt reacted with inorganic acid, formed acid salt /inorganic acid(molar ratio) = 3:1, reaction temperature was 30 ℃, the macroporous silica gel product with bimodal pore distribution can be obtained, the pore volume was 1.65 cm³/g, pore radius was 20.00 nm and specific surface area was 340 m²/g.