Abstract: 100 samples of tobacco rhizosphere soil were collected from Fujian, Henan, Anhui, Yunnan and Hubei, 62 chitinase producing strains, including 32 fungi, 22 bacteria and 8 actinomyces, were isolated by chitin selective medium. The strains were screened with transparent zone and reducing sugar methods. The results showed that the chitinases produced by Streplomyces sp had the highest activity. The inhibition actions of the strains, which produced chitinases with high activity, to Alternaria alternata (Freis) Keissler and Phytophthora parasitica Dast var. nicotianae were determined. The strains, 9-1-1, 9-2-1, and 19-2-1, showed inhibition action to Phytophthora parasitica Dast var. nicotianae at different degress, headed by strain 9-1-1; however, they had no inhibition action to Alternaria alternata (Freis) Keissler. Strain 9-1-1 had the potential of becoming a biofungicide against Phytophthora parasitica Dast var. nicotianae.