The invention discloses a feed additive with a release effect and capable of treating sow metritis. The feed additive is prepared from the following components: soybean pulp, corn, grape skin pomace, astilbe chinensis, herba leonuri, radix angelicae sinensis, cortex ilicis rotundae, ossa draconis, fructus ligustri lucidi, rhizoma atractylodis macrocephalae, herb of adnate elder, herba salviae chinensis, herba taraxaci, rhizoma zingiberis recens, fructus crataegi, pericarpium citri reticulatae, fructus jujubae, silkworm chrysalis, sodium alginate, chitosan, starch, magnesium stearate and sucrose ester. The preparation method comprises the following steps: material preparation, extraction of effective components of traditional Chinese medicine bulk drug, pelleting, tabletting and pelleting. The feed additive disclosed by the invention is capable of resisting bacteria, diminishing inflammation, activating blood circulation, removing blood stasis, draining toxin, expelling pus, invigorating spleen-stomach and replenishing qi, and is capable of effectively treating the sow metritis; durable and slow in-vivo drug release can be realized, the blood concentration is stable, and the fluctuation is small, so that the dosing frequency is reduced, the concentration of effective drug components in blood is controlled so as to maintain the pharmacological function, the peak times of drug release are reduced, and certain protection is carried out on visceral organs of sows and piglets.