The invention discloses a method for extracting dendropanax dentiger(harms)merr leaf active ingredients with a reaction kettle and an active ingredient application; distilled water is used as a solvent, stirring and extraction are carried out in the reaction kettle, then leaching is carried out with petroleum ether, ethyl acetate and n-butanol successively, and thus the yellow dendropanax dentiger(harms)merr leaf active ingredients are obtained. The dendropanax dentiger(harms)merr leaf active ingredients have a main component of saponin, about 24 g of the dendropanax dentiger(harms)merr leaf active ingredients can be extracted from per kg of a dendropanax dentiger(harms)merr leaf powder, and the content of saponin in per g of the dendropanax dentiger(harms)merr leaf active ingredients is about 630 mg; the extraction method is simple, the extraction efficiency is high, and the extracted active ingredients have the effect of improving the immunity of rabbits.