Abstract: The physiological races of 30 Phytophthora parasitica var. nicotianae strains were isolated from 111 samples in Xiangfan, Enshi and other major tobacco area of Hubei, and identified by zoospore suspension inoculation and TTZ (2,3,5-tripheny ltetrazolium chloride) color reaction. The results showed that all these 30 strains were presented red reaction in TTZ medium. And according to the reaction on the differential host, 24 strains belonged to physiological race 1 and were the Dominant race, which take up 80 percent in all strains. The other 6 stains showed different pathogenicity to L8 and NC1071: 1 strain was resisted by L8 and NC1071; 1 strain had high pathogenicity to NC1071 and was middle resisted by L8; 1 strain had high pathogenicity to L8 and middle resisted by NC1071; 3 strains had middle high pathogenicity to NC1071 and were middle resisted by L8, which needs further study to make sure their races.