In order to investigate the growth characteristics and understand the survival strategies and invasiveness of invasive plant under the climate warming conditions, the invasive plant Eupatorium catarium was mixed cropping with its accompanying plant Lagedium sibiricum, three simulated warming patterns (increase 2 ℃ in the daytime of 07:00–19:00, increase 2 ℃ in the nighttime of 19:00–07:00 and increase 2 ℃ in the daytime of 07:00–19:00 and in the nighttime of 19:00–07:00) were conducted and the plant height, root length, leaf number, module biomass and the interspecific competition of Eupatorium catarium were measured. The main results were as follows: the increasing of temperature had not only promoted the stem height and root length of Eupatorium catarium obviously, but also increased its leaf number and leaf area. Daily warming (07:00–19:00, 2 ℃) had the most effect on its growth and morphological features. When mixed with Lagedium sibiricum, the plant height, the total biomass, the relative yield, the total relative yield of Eupatorium catarium were much higher than those of the monoculture. The interspecific competitiveness of Eupatorium catarium was enhanced with the increasement of the mix ratio of Eupatorium catarium and Lagedium sibiricum, which showed a certain dependency to the the mix ratio. Under the condition of warming and normal temperature, the interspecific competitiveness of Eupatorium catarium with low mix ratio was less than zero and independent the environment. It manifested that Eupatorium catarium had strong morphological plasticity which affected the invasion ability, and might rapidly colonize and expansion by adapting climate warming environment.