The invention discloses a weaned lamb forage and a preparation method thereof. The weaned lamb forage is composed of the following raw materials, by weight, 45-55 parts of corn straw, 30-40 parts of Pennisetum sinese Roxb, 15-25 parts of Black Locust leaf, 5-10 parts of Herba Leonuri, 10-20 parts of sweet potato residue, 10-15 parts of brewer's grain, 20-30 parts of peanut hull powder, 1-2 parts of a starter, 40-50 parts of corn flour, 20-25 parts of wheat bran, 10-15 parts of soybean meal, 4-6 parts of a lyophilized powder additive, 3-5 parts of fried rice flour, 5-8 parts of MaiFan stone, 2-4 parts of mandarin oil, 3-6 parts of sodium alginate, 0.2-0.3 parts of calcium carbonate, 0.3-0.4 parts of potassium hydrogen phosphate and 0.3-0.5 parts of salt. The forage contains all nutrition required by the growth of weaned lambs, guarantees the healthy production of the weaned lambs, provides healthcare values, and raises the growth speed of the weaned lambs.