Abstract: A comparative study was conducted on the allelopathic effects of water extracts from an invasive species (Solidago canadensis L.) and native species (S.decurrens Lour.) on seed germination and seedling growth of six native plants.The results showed that the allelopathic inhibitory effects of the extracts from both below and above ground parts of S.canadensis were enhanced with increasing concentration.Native S.decurrens showed the same trend as S.canadensis,but in the extracts of S.canadensis from below ground had stronger allelopathic activity to seed germination and seedling growth of native plants compare to S.decurrens.Extracts of S.decurrens from above ground,however,showed stronger inhibition.Our results suggest that S.canadensis may become the monodominant community in invasive areas due to allelopathy,which may play an important role in the successful invasion of S.canadensis in China.Since species of Fabaceae were not sensitive to the water extracts of S.canadensis,they could be used as the priority species in biological replacement control.