Ruminant animal concentrated feed is composed of, by weight, 50-80% of sugarcane tip leaves, 15-30% of cassava leaves and 5-20% of molasses. A preparation method of the ruminant animal concentrated feed includes of smashing of the sugarcane tip leaves and cassava leaves, pre-spraying, steam explosion, primary fermentation, secondary fermentation, drying, smashing and granulating. With sugar-refining industry by-products and cassava by-products being raw materials, the ruminant animal concentrated feed is prepared by the adoption of a method of steam explosion and biological fermentation combination; the obtained feed contains rich protein, further contains kinds of amino acid, flavonoid substances, sugar, grease, alcohol and others, and is high in nutritive value, good in palatability and good in digestion performance. In addition, the ruminant animal concentrated feed contains fungi, active ferment and kinds of digestive enzymes beneficial to intestines, can improve intestinal flora of animals and enhance the immunity of the animals, and is a animal protein feed having a health-care function.