The invention relates to coarse food grain black sesame paste and a preparation method thereof. The coarse food grain black sesame paste is prepared from the following raw materials in parts by weight: 80 to 90 parts of black sesame, 20 to 25 parts of millet, 23 to 25 parts of black rice, 15 to 20 parts of sorghum, 10 to 12 parts of oats, 2 to 3 parts of bran submicron powder, 24 to 26 parts of steamed bun, 3 to 4 parts of hawthorn berry powder, 4.5 to 6 parts of pork powder, 4 to 5 parts of green vegetables, 3 to 4 parts of potentilla chinensis, 1 to 2 parts of cortex albiziae, 2 to 3 parts of polygala tenuifolia, 2.5 to 4 parts of Chinese wild ginger, 3 to 4 parts of lotus stamen, 4 to 6 parts of immature bitter oranges, 3 to 4 parts of green tea, 1 to 2 parts of raspberry, 5 to 6 parts of osmanthus fragrans and 5 to 6 parts of pomegranate wine. Multiple coarse grains are added into the black sesame paste, so that the fiber content is high, the intestines and the stomach can be conditioned, and the digestion can be favored; in addition, the coarse food grain black sesame paste has the functions on dispelling melancholy, tranquilizing mind, promoting intelligence, eliminating phlegm, mitigating edema, expelling wind, removing cold, inducing resuscitation, strengthening kidney, arresting seminal emission, replenishing liver, nourishing the kidney, controlling nocturnal emission with astringent drugs, and improving the eyesight.