To investigate the resistant effect of silicon on leaves of two rice varieties with nanometer SiO₂ inoculation treatment against Magnaporthe grisea, resistant variety Nongda 18 to M. grisea and susceptible variety Mongolian rice to the pathogenic fungus were observed with SEM and TEM compared with control groups without the SiO₂ treatment. The findings showed there were only a few hyphae of M. grisea on both leaves, and less hypha quantities than control group without Si treatment. Based on TEM pictures, it was clearly observed that Si might prevent the hypha from penetration by enclosing hypha around sites penetrated. Consequently, the result indicated that nanometer SiO₂ was able to protect rice from the pathogentic fungus.