Abstract: The allelopathic potentials of alcohol extracts from Wedelia trilobata to economic crops and pathogenic fungus were investigated to determine the role of allelopathy in successful invasion. The results showed that the four alcohol extracts from Wedelia trilobata dry stems, dry leaves, wet stems and wet leaves all had different inhibitory effects on the rape of seed vigor index. Alcohol extracts from wet leaves and dry leaves had different inhibitory effects on the tomato of seed vigor index. The four alcohol extracts all have obvious inhibitory effect on the growth of Rhizoctonia solani. Alcohol extracts from wet leaves and dry stems have inhibitory effect on the growth of Fusarium oxysporium f.sp.niveum, but the alcohol extracts of dry stems and wet leaves promote the growth of Fusarium oxysporium f.sp.niveum.