The invention discloses a natural plant feed additive for stock boars. The additive disclosed by the invention is prepared from the following components: semen plantaginis, wolfberry fruits, dodder, magnolia vine fruits, Chinese chive seeds, fenugreek seeds, lotus seeds, clove, wrinkled gianthyssop, cyperus rotundus, white hyaciath beans, mint, lotus leaves, cortex lycii radices, angelica sinensis, astragalus root, fructus psoraleae, cortex eucommiae and drynaria fortunei. The additive disclosed by the invention can gradually increase the semen collection and the amount of sperms of the boars, enable the activity of the sperms to gradually tend to a high-level stable state, reduce the sperm deformity rate and prolong the survival time and effective survival time of the sperms.