Abstract:Abstracts:Solidago canadensis and Conyza canadensisare two typical harmful alien species. In this article, a comparative analysis of the growth potential, allelopathy, invasion and dispersal mechanisms between the two species was conducted. Results showed that Solidago canadensis can reproduce either sexually or asexually while Conyza canadensismainly reproduces by seeds, with seed yield much higher than that of Solidago Canadensis;Both of their plant water extracts had strong allelopathic effects; However, the allelepathy of Solidago canadensis was relatively stronger than that of Conyza canadensis.Both species could spread in space by natural dispersal or human transportation, but Conyza canadensis had a relatively stronger ability to adapt to environmental change and thus can spread much faster in the field.