Abstract: For the study of griseofulvin inhibition of Magnaprothe grisea and the control effect on Magnaprothe grisea, agar block method were used to detect the inhibition of Penicillium patulum GM120- 43 against Magnaprothe grisea, griseofulvin control the potted rice blast. The results indicated that, Penicillium patulum GM120-43 had larger inhibition on Magnaprothe grisea, the control effect of griseofulvin on leaf blast and panicle blast, griseofulvin prevent leaf blast and panicle blast when 300-fold dilution effect were 93.76% and 53.79%, treatment were 89.2% and 49.21%. When it was tested in the concentration range, griseofulvin control effect was proportional to its concentration. Griseofulvin was a kind of promising biological pesticide.