Abstract: Fourty four pathogenic strains of Ralstonia solanacearum were isolated from typical diseased tobacco plants in Qianjiang,Youyang and Wulong of Chongqing and preliminarily identified.According to their effects on hosts,infiltration reaction,melanin formation,all the strains were preliminarily referred to physiological race 1,among them,35 strains were high pathogenicity to all kinds of identified host.There were 10 strains whose average disease indexes against 6 kinds of identified hosts were over 90,distributed in Shuitian Village and Xinghua Village of Qianjiang and Huangying Village and Xiannushan Town of Wulong.