Abstract: In order to study the effects of garlic intercropping on soil microbial communities, including pathogens of tobacco root and stem diseases and tobacco quality, field trials were conducted in Longyan of Fujian in China. The results showed that the numbers of bacteria and fungi decreased in garlic intercropping fields. In particular, the numbers of tobacco pathogens Ralstonia solanacearum E.F.Smith and Phytophthora parasitica var. nicotianae were also reduced (betweeen 24.46×10⁴ and 27.67×10⁴ cfu/gor betweeen 29.76×10³ and 63.52×10³ cfu/g, respectively) in the soil of tobacco fields intercropping with garlic. The number of actinomycete, on ther other hand, was promoted by intercropping with garlic in fields. The quality of tobacco leaves was not affected negatively. The results suggest that the tobacco pathogens Ralstonia solanacearum E.F.Smith and Phytophthora parasitica var. nicotianae are inhibited by garlic intercropping. Therefore, we may take advantage of garlic intercropping to control the diseases of tobacco root and stem. With less usage of chemical pesticides, this approach could enhance the safety of tobacco leaves and protect environment.