Abstract: 44 strains of Ralstonia solanacearum were isolated from typical diseased tobacco plants in Qianjiang district, Youyang and Wulong counties of Chongqing.The results of flagellum coloring and path ogenicity determining showed that the 44 strains were morphologically identical with Ralstonia solanacearum, and all the sestrains were pathogenic.By further studying the capacity of the strains in the utilization of disaccharide(maltose, lactose and cellobios) and hexyl alcohol (mannitol, dulcitol and sorbitol), the deoxidization to KNO₃ and gas production, it was found that all the 44 strains belonged to Bio type Ⅲ.