The objective of this research were to (i) investigate the effective of polyphenol in prevention of Pyricularia oryzae fungus caused blast disease on rice and (ii) examine the ability of rice plant growth promotion. The antifungal ability of polyphenol was examined with 5 replications in Laboratory condition. The results found that polyphenol 2% and 4% reduced mycelia growth of blast fungus with diameter of mycelia growth on Oatmeal medium reaches 45.0mm and 44.6mm at 9 days after inoculation. On the other hand, polyphenol2% and 4% could also reduce the spore germination of P. oryzae on Oatmeal medium with ratio of spore germination reaches 22,2% and 22,2% at 48 hours after inoculation. On the other hand, the ability of plant growth promotion was detected with 5 replications in Laboratory condition. The results showed that polyphenol 2% and 4% have plant growth-promoting ability such as ratio of germination, shoot length, root length and dry weight root higher than the control treatments.