The invention discloses a method for improving functional components in lamb by feeding sweet sorghum silage diet, and relates to the technical field of lamb diet formulas. In the feed formula, the roughage are sweet sorghum silage and alfalfa pellets, and the composition of concentrate supplement by mass percentage is as follows: 41% of corn, 10% of bran, 32% of soybean meal, 5% of rapeseed meal, 1% of expanded urea, 1% of stone powder, 2% of salt and 8% of premix. The feeding management method is as follows: deworming treatment is carried out on lamb pups before feeding; Feeding is carried out in a whole house, so that lamb can freely eat sorghum silage; The daily feeding amount is adjusted according to the feeding amount of lamb the day before; The concentrate supplement and alfalfa granules are fed twice according to 1% and 0.5% of animal weight and the lamb drink water freely and the pens are disinfected regularly. The method has that beneficial effect that the method has significant influence on the content of amino acids and fatty acid of lamb, and the method can promote the output of high-quality lamb which is beneficial to human health.