Abstract: To find the relationship between Solidago canadensis L. allelopathy and resource competitiveness in the process of invasion, allelopathy and competition separation-based bioassay (ACS) approach was used to analyze S. canadensis L. response under different nitrogen supply. The results show that the invasive plant S. canadensis L. has a high ability to interfere with target wheat plant. It is highly stable and very competitive, and its allelopathic potential increases with decreasing nitrogen supply in cocultured systems. The reverse is true for the native species of S. decurrens Lour., which has a lower allelopathic potential at all nitrogen supply levels and a low resource competitiveness under normal to rich nitrogen supply. However, S. decurrens Lour. has a remarkably high ability to compete for resources under low nitrogen supply, believed to be induced by co-culture system competition.