The invention discloses a compound feed capable of preventing streptococcal diseases of Tilapia and a preparation method of the compound feed. The feed comprises the following components in percentage by weight: 4-8% of fish meal, 22-28% of soybean meal, 4-8% of sesame seed meal, 12-16% of corn flour, 8-10% of cotton seed cakes, 15-18% of peanut kernel meal, 13-17% of whole wheat flour, 1-2% of calcium dihydrogen phosphate, 2-4% of a premix, 1-3% of soybean oil, 0.2-0.5% of plantain herb, 0.2-0.5% of common andrographis herb and 0.2-0.5% of large bamboo leaves. The compound feed disclosed by the invention is used for breeding the Tilapia at an adult fish period, and is balanced in nutrition and reasonable in compounding ratio; Chinese herbal medicine components including the plantain herb, the common andrographis herb, the large bamboo leaves and the like are particularly added, so that the health of intestinal tracts of larval Tilapia can be effectively protected, the liver functions of the Tilapia are strengthened, the immunity of Tilapia bodies is enhanced, the capacity of the Tilapia for resisting the streptococcal diseases is improved, and the growth is promoted.