Pot-experiments were conducted to study the amelioration of dolomite on soil acidity of flue-cured tobacco. The result showed that with the increase of dosage and decrease of particle size of dolomite, the amelioration effect became more obvious. Dolomite should be used 30 days before tobacco transplanting. If the soil pH value adjustment target is 1 unit or the application of dolomite is 1 500 kg/hm2, the particle size of 250 μm dolomite powder was more economic. As the pH value of soil, the exchangeable Al content can more reflect the growth of tobacco plant, its critical indicators is 0.30–0.45 cmol/kg, if the content is higher than the critical value, dolomite should be used to adjust acidity.