Abstract: The experiment was conducted to find the effects of water extract of Eupatorium adenophorum (Spreng.) leaf and leaf litter on the germination and seedling growth of Bidens pilosa L. and to explore allelopathic effects of Eupatorium adenophorum (Spreng.) on Bidens pilosa L. Results showed that the water extract of Eupatorium adenophorum (Spreng.) leaf had certain inhibitory effect on seed germination of Bidens pilosa L., with the increase of concentration, the seed germination rate decreased gradually, when the concentration was 3%, the seeds could not germinate; inhibitory effect on the radicle was superior to that on the germ, and showed weak promotion effect on the growth of the seedlings. The inhibition effects of extract of litter on seed germination was weaker than that of leaf water extracts, with the increase in litter amount, Bidens pilosa L. grew better and accumulation of material in the plant was promoted. The conclusion suggests that the Bidens pilosa L. grow well on the ground invaded by Eupatorium adenophorum (Spreng.), so Bidens pilosa L. can be used instead of Eupatorium adenophorum (Spreng.), plays a role in the prevention and control of Eupatorium adenophorum (Spreng.).