The invention provides a feed for improving the immunity of a black muscovy duck and a preparation method thereof. The feed is obtained by grinding and mixing the following raw materials: 100-120 parts of wheat brans, 80-100 parts of bean cake, 10-20 parts of lysine, 5-10 parts of tryptophan, 5-10 parts of methionine, 5-10 parts of Chinese angelica roots, 10-20 parts of clinacanthus nutans, 1-2 parts of bacillus, 1-2 parts of lactic acid bacteria, 1-2 parts of vitamin A, 1-2 parts of vitamin E and 1-2 parts of vitamin C. According to the feed, amino acid, Chinese angelica roots, clinacanthus nutans, bacillus, lactic acid bacteria and vitamins are added into daily ration of the black muscovy duck, the different requirements on the nutrition of the black muscovy duck during different growth and physiology periods can be met, meanwhile, the feed nutrition is balanced in an emphasis manner, the quality of the black muscovy duck can be effectively improved, and the immunity is improved, so that the feeding cost is lowered, and the culture benefits are improved.