Abstract: To study the effect of combination of growth promoting bacteria and organic fertilizer on the exchangeable calcium (Ca) and magnesium (Mg) in tobacco planting soil, a two-factor complete design, which included bacteria and 6 types of organic fertilizers, was adopted to analyze the changes of Ca and Mg content and the ratio of Ca/Mg in the cultivated soil through the three growth periods of tobacco. The results showed that the contents of exchangeable Ca and Mg in the studied area were at very low level. Compared with the single application of organic fertilizer, the exchangeable Ca content in soil applied with growth promoting bacteria and mushroom residue increased by 11.50% (P<0.05) in the vigorous growing stage, and the contents of exchangeable Ca and Mg in soil applied with growth promoting bacteria and amino acid organic fertilizer increased by 22.70% (P<0.05) and 29.67% (P<0.05), respectively. In the mature stage of tobacco, the content of exchangeable Ca in soil applied with growth promoting bacteria and cow dung increased by 21.29% (P< 0.05), and the content of exchangeable Mg in soil applied with growth promoting bacteria and shrimp peptide organic fertilizer increased by 14.96% (P<0.05) and the Ca/Mg ratio decreased significantly. The contents of exchangeable Ca and Mg and Ca/Mg ratio in soil applied with growth promoting bacteria and organic fertilizer in other growing periods of tobacco were not significant or decreased. In addition, the exchangeable Ca, Mg and Ca/Mg ratio in soil applied with growth promoting bacteria and cow dung were the highest or second highest in 6 combined treatments. To sum up, combination of growth promoting bacteria and cow dung is more suitable for the studied area because the contents exchangeable Ca and Mg in soil are at a high level in the three growing stages of tobacco, and the coordination between Ca and Mg is the strongest.