The invention discloses a complete formula granulated feed for beef cattle and a preparation method thereof. The complete formula granulated feed for beef cattle comprises the following components in percentage by weight: 25 to 35 percent of chaff, 15 to 20 percent of brewer's grains, 10 to 20 percent of malt root, 8 to 16 percent of wheat shorts, 7 to 15 percent of soybean hulls, 5 to 10 percent of palm kemel cake, 5 to 8 percent of molasses, 1 to 3 percent of urea, 1 to 2 percent of premix, 0.5 to 1.5 percent of bentonite. The preparation method comprises the following steps: crushing, mixing and stirring the materials; pressing the mixture into granules directly by adopting a granulator; and cooling, drying and storing. The complete formula granulated feed for the beef cattle has the advantages of balanced nutrition, proper energy content, high growing speed, high dry matter digestibility, good palatability, low moisture content (less than or equal to 13 percent) and easiness for transportation and storage. The complete formula granulated feed for the beef cattle can be used for feeding and fattening the beef cattle in growing and finishing stages, and can not be used in breeding cattle, so that the production cost for the beef cattle can be reduced, the fattening benefit for the beef cattle can be improved, and the production efficiency of the beef cattle can be improved.