The aim of this research is to study the impact of invasive species Ambrosia trifida on the vitality of Polygonatum stenophyllum which is endangered species. We removed the cover degree of the invasive species at different levels(C, T1, T2) in the natural habitat where both invasive plant and endangered species and observed ecological responses of P. stenophyllum for two years. C(control) which removed none of A. trifida, T1(treatment 1) removed 40~60% coverage of A. trifida and T2(treatment 2) removed all A. trifida. Plant species number, shoot length, aboveground biomass weight, shoot weight, leaf weight, fruit weight, fruit number, seed weight, fruit number, seed number per fruit were higher in the treatments of removed invasive plant cover(T1, T2) than control(C) that didn't remove it both the first year and the second year(p<0.05). However, death rate and seed weight between the control(C) and treatment(T1, T2) were almost same in the first year but showed difference in second year. This result reveals that the A. trifida has significant impact on the performance reduction of Polygonatum stenophyllum. In conclusion, removal of more than 40% of invasive plant cover degree is required to conserve the endangered species.