The invention discloses a feed additive, an antibiotic-free laying chick mixed feed, and a preparation method of the mixed feed. The feed comprises pre-gelatinized brown rice, puffed corn, whole potato flour, wheat flour, puffed soybeans, fermented soybean meal, super steamed fishmeal, rice protein powder, emulsified coconut oil powder, calcium carbonate, calcium dihydrogen phosphate, sodium chloride, a trace element premix, a vitamin premix, lysine, methionine, a composite acidifier, a composite enzyme preparation and the feed additive; and raw materials of the feed additive comprise garlicin, origanum oil, Flammulina velutipes polysaccharides, Macleaya cordata alkaloids, Artemisia carvifolia, antifeverile dichroa root, Agrimonia eupatoria, radix bupleuri, chitosan oligosaccharides and taurine. The feed does not contain antibiotics, the anti-nutritional factors of the raw materials of the feed are low, and most raw materials are preprocessed, so the safety and the palatability of the raw materials are improved, the feed intake of chicks is improved, and the feed has high utilization rate and high uniformity.