Abstract: Field experiments of mixed-and pure-cropping of four rice varieties,including hybrid varieties and traditional high-quality varieties which had diverse genetic backgrounds,were conducted to study the controlling effects of variety diversity on the rice blast in Ji’an County and Shicheng County on the basis of analysis on resistance gene analogue and the mechanism of stabilizing function of variety diversity to the plant pathogen.The results demonstrate that the appropriate mixed-cropping of rice varieties with different genetic backgrounds has a significant controlling effect on the occurrence of the rice blast,particularly for the highly susceptible traditional varieties.A significant decrease of incidence and disease index of rice blast are observed and the control efficiency is as high as 82.14%～95.91%.The control efficiencies of mixed-cropping of hybrid rice on rice blast are 40.82%～70.87% while the yield increases by 6.03%～11.81%.