Abstract: The pathogenicity of rice blast fungus has an obvious differentiation, and there are many physiological races, which vary frequently. That is one of the most primary reasons that results in the comedown of the resistance of rice variety, which become sensitive to rice blast disease, sequentially. Three hundreds and eight monoconidial isolates were obtained from rice blast specimens collected from Anhui province in 2002. The physiological races of the isolates were identified with seven Chinese differential rice cultivars in vivo and in vitro; the results showed that the conclusion of identification in vivo and in vitro is substantial agreement. There are eight group physiological races in Anhui province, that is ZA、ZB、ZC、ZD、ZE、ZF、ZG and ZH, respectively. The dominating group was ZB, and the dominating physiological races were ZB13 and ZB15. The physiological races of Pyricularia grisea occurred differently on various rice cultivars. The effects of keeping rice-leaves fresh of Benzimidazole, 6-BA, IAA and NAA were tested and the results were that the effect of 6-BA was the best which could keep the leaves fresh for 13 days, and it did not inhibit the disease potential, so 6-BA is adapted for inoculating the rice blast fungus in vitro.