The invention relates to a granular feed and a preparation method thereof. The shape of the granular feed is selected from one or more of a cylinder, a triangular prism, a cuboid and a shape with an irregular cross section, the diameter or the equivalent circle diameter of the granular feed is 2.5-4.5mm but does not include 2.5mm, and the length of the granular feed is 3-5 times of the diameter or the equivalent diameter. The granular feed is prepared from the following raw materials in percentage by weight: 90-94% of fermented raw materials, 2-3% of soybean oil, 1-1.5% of fish meal and 2-6% of a premix agent. The preparation method of the granular feed comprises the following steps of preparing the fermented raw materials, performing heating treatment, performing granulation, performing cooling and performing screening. Compared with the prior art, the granular feed disclosed by the invention is reasonable in nutrition collocation, and can significantly promote foraging, condition the functions of the intestines and the stomach, enhance the organism immunity and improve the growth properties of pigs.