Abstract: Four kinds of Asteraceae were used as experimental materials, and the extracts of them were extracted with petroleum ether and ethyl acetate respectively. The antibacterial activity of different extracts on 5 kinds of Juglans regia was determined by the growth rate method. The virulence regression equation and semi-inhibitory concentration of different extracts on 5 kinds of J. regia. Four kinds of Asteraceae were used as experimental materials, and the extracts of them were extracted with petroleum ether and ethyl acetate respectively. The antibacterial activity of different extracts on 5 kinds of J. regia was determined by the growth rate method. The virulence regression equation and semi-inhibitory concentration of different extracts on 5 kinds of J. regia pathogenic fungi were calculated by SPSS 19. The results show that 4 kinds extracts have certain inhibitory effects on mycelium growth of the 5 pathogens. The petroleum extract of Conyza canadensis has the strongest inhibitory effects on the Fusicoccum persicae, Ascochyta sp., Colletotrichum gloeosporioides, and the inhibition rate reached 77.5%, 81.6% and 79.5%, and the EC₅₀ are 1.31, 1.34, 0.71 mg/mL. The petroleum extract of Cosmos bipinnata has the strongest inhibitory effect on the Phyllosticta sp., the inhibition rate is 74.1%, and the EC₅₀ is 0.56 mg/mL. The ethyl acetate extract of Conyza canadensis has the strongest inhibitory effects on the Phyllosticta sp., the inhibition rate is 61.8%, the EC₅₀ is 3.63 mg/mL.