The invention belongs to the technical field of tail gas processing, and especially relates to a purifying method of fermented forage production tail gas. The purifying method of fermented forage production tail gas comprises four steps: cloth bag dedusting, alkali solution adsorption, high pressure spray adsorption, and biological liquid spray, and is used for purifying processing of dust, and gas of peculiar smell such as olatile organic acids, hydrogen sulfide gas, alcohols, and esters. The purifying method is high in tail gas peculiar smell removing rate, low in cost, and high in efficiency, and is suitable for large scale popularization applications in the field of fermented forage industry, and no secondary pollution is caused.