The invention provides a marinating material for processing a marinated duck and a preparation method thereof and relates to the technical field of food seasonings. The marinating material comprises spices and seasonings. The spices comprise root of red-rooted salvia, radix ophiopogonis, fennel, amomum globosum loureiro, licorice root, siraitia grosvenorii, myrcia, Chinese prickly ash, Danxiangmu and coriander seed. The seasonings comprise cooking wine, soy sauce, pepper powder, kaempferiae powder, soup-stock, garlic powder, table salt, white sugar, monosodium glutamate and sesame oil. The marinated duck prepared by the marinating material is different in color, fragrance and taste, has a unique flavor, is delicious and smooth, has a mellow, crisp and tender taste, has harmonious spice fragrance and duck meat taste and has good meat color and good taste.