Abstract: In order to exploit new botanic fungicide, the antifungal activities of the ethanol extracts of stem-leaf and rhizoid of P. commune were studied by the mycelia growth rate method and the spore germination method based on the determination of their mycelia growth inhibition rates, spore germination inhibition rates and median inhibition concentration values (EC₅₀) on B. cinerea, F. solani f. sp. Batatas, F. solani and A. brassicicola. The results showed that the antifungal activities of the ethanol extracts of P. commune against the four plant pathogenic fungi were extremely significant (P<0.01) in the concentration range of 1 to 8 mg/mL and the antifungal activities were proportional to the concentration of ethanol extracts of P. commune. Furthermore, under the same concentration, the antifungal activity of the alcohol extracts of the stem-leaf of P. commune against the four plant pathogenic fungi was significantly higher than that of the rhizoid of P. commune (P<0.05). Finally, among the four plant pathogenic fungi, F. solani f. sp. batatas was the most sensitive to the antifungal activity of the ethanol extracts of the stem-leaf and rhizoid of P. commune, with the EC₅₀ values of stem-leaf and rhizoid only 0.42 and 0.35 mg/mL, respectively. In summary, the ethanol extracts of the stem-leaf and rhizoid of P. commune had strong antifungal activities against the four plant pathogenic fungi, and the antifungal activity of the stem-leaf was better than that of the rhizoid. Both of them had certain potential application in the development of new botanical fungicides.