The invention discloses a special feed for mutton sheep in a fattening period, and relates to the technical field of preparation of special feeds for mutton sheep in the fattening period. The formula of the feed comprises the following raw materials in percentage by mass: 20-40% of fermented mulberry powder, 15-35% of whole corn silage powder, 0-10% of alfalfa hay powder, 0-5% of Guimu-1 hybrid pennisetum urpureum powder, 0-5% of bean pulp, 5-15% of rice bran and hull, 5-10% of brewers' dried grains and 5% of mutton sheep premix, wherein the total mass of the raw materials is 100%. The preparation method of the feed is simple; and the feed is mainly used for raising and fattening mutton sheep in growth and fattening periods, can obviously reduce the consumption of grain protein powder, reduce the cholesterol content of mutton and reduce the breeding cost under the condition that the production performance of the mutton sheep is not reduced, can further balance the daily ration structure, and achieves the fattening effects of increasing the daily gain, improving the slaughter rate and shortening the fattening period.