Abstract: To address the problem of the difficulty in controlling the invasive plant Solidago canadensis due to its lignified stems and well-developed root system at the mature stage, this study conducted a field experiment to systematically evaluate the control effects of 14 herbicide combinations, aiming to screen out highly effective and long-lasting herbicide combinations. The experiment was carried out in a typical invasive habitat, with 14 herbicide combinations(T₁~T₁₄) and one water control. The above-ground damage, fresh weight of plants, root mortality rate, and the number of new shoots were monitored at 15, 30, 60 and 90 days after application, and the plant control efficacy and fresh weight control efficacy were calculated. The results showed that there were significant differences in control efficacy among different combinations. T₄(31% benzoylpyrazole·glyphosate) had outstanding quick-acting efficacy, with plant control efficacy and fresh weight control efficacy of 81.82% and 85.70% respectively at 15 days after application. By 90 days after application, T₄, T₁₀(40% fluorochloridone·chlorflur EC + 43% glyphosate potassium salt AS + adjuvant), and T₁₄(70% glyphosate + triclopyr SP+ adjuvant) all achieved 100% root mortality and no new plants, demonstrating complete control efficacy. T₅~T₈(24% aminocyclopyrachlor AS+10% bixenzate OD+ adjuvant) had initial plant control efficacy below 10.00%, but effectively suppressed new shoots. By the end, the root mortality rate was 63.20%~89.78% and no new plants, exhibiting a delayed but persistent control characteristic. Correlation analysis further revealed no significant linear correlation between root mortality and the number of newly emerged plants, indicating that for mature S. canadensis, "complete kill" and "regrowth suppression" are relatively independent dimensions of control efficacy. This study deepens the understanding of herbicide efficacy from the perspectives of action patterns and mechanisms, providing a basis for herbicide selection and theoretical support for constructing an Integrated Pest Management(IPM) technology system based on chemical control for invasive species.