Abstract: Twenty species of plant extracts were tested for their fungitoxity against Phytophthora infestans in this study. Preliminary results showed that 9 of 20 plant extracts showed significant inhibitory effects on sporangia germination and 6 of 20 plant extracts showed significant inhibitory effects sporangia forming of P. infestans. Four species of the plant extracts including Ts-86, Ts-39, Ts-109 and Ts-121 showed equivalent strong inhibitory effects with the chemical control-“Ridomil” 3000 times dilution were further tested on slides for their inhibitory effects on sporangia germination and production of P. infestans. The extract Ts-86 showed equivalent strong inhibitory effects with the chemical control-“Ridomil” 3000 times dilution, and significantly stronger than the other three extracts.