Sichuan, Chongqing and Guizhou are among the most important areas for rice blast disease (Magnaporthe oryzae) to take place and cause losses. To investigate the difference in the virulence of blast fungus between the different regions, it will be benefit for prolonging the use of resistance cultivars. In 2012 and 2013, 24 monogenic lines of rice for blast resistance of the common background of Lijiangxintuan Heigu (LTH) were planted at the locations of frequent epidemic of blast disease in 21 counties of Sichuan province and Chongqing city. In 2014 and 2015, panicle blast specimens were collected from totally 47 paddy fields from 15 counties in whole Guizhou provice, 10 counties in the northern part of Sichuan Province and 2 counties in Shandong provinces and immersed in water for 4 hours before they were inoculated on the arrays of 16 varieties and the 24 monogenic lines of rice. After the mulching and complete segregation by plastic membrane for 40 days, to investigate the rice blast incidences of 16 varieties and the 24 monogenic lines, The sesult of experiment in 2012 and 2013 indicate that resistance gene Pi2 was then found to express the resistance in 38. 10 % of the disease nurseries. The rice blast identification results of panicle blast specimens which collecting form Sichan, Gui/hou and other place indicate that resistance genes Pile, Pik*, and PiKm were found to be resistant to blast fungus respectively from 51.85 %, 48. 15 % and 48. 15 % of the disease fields in (iui/lum. PiKm, Pi2, Pi9, Pile, and Pile' were resistant to the blast fungus respectively from 70. (K) % . 60. 00 %, 50. 00 %, 50. 00 % ami 45. (X) % of the disease fields in Sichuan. The frequency for PQ to be resistant to the blast fungus from fields in northern part of Sichuan was significantly higher than that in Guizhou (/' = 0. 0066). The frequencies for 3 differential host varieties i. e. Chenghui 448, Neihui 99-14 and HHH-1, to be resistant to blast fungus from the fields in Guizhou and northern part of Sichuan were respectively 74. 07 %, 70. 37 % and 70. 37 % vs. 90. 00 %, 70. 00 % and 90. 00 %, which were significantly higher than that for other three differential host varieties, i. e. IK24, Minghui 63 and Duohui No. 1. The frequencies for 10 hybrid rice varieties to express the resistance to blast fungus from the fields in Guizhou and northern part of Sichuan varies respectively between 81.48 % -92. 59 % and 90. 00 % - 100. 00 9e . While the cluster analysis of the virulence of blast fungus in the disease nurseries and paddy fields had indicated the bigger difference in virulence roughly in accordance to the geographic distance, the virulence of blast fungus from the different fields in same county and even the same sampling sites could be significantly different. On the other hand, the blast fungus from different counties and different provinces could be virulent to all of the 24 monogenic lines and the further differentiation of the virulence relied on other rice varieties. [ABSTRACT FROM AUTHOR]