The invention discloses a crab feed rich in organic selenium and a preparation method thereof. The crab feed is characterized by being prepared from the following raw materials in parts by weight: 20 to 25 parts of soybean meal, 19 to 24 parts of rice bran, 15 to 17 parts of water chestnut, 13 to 16 parts of pine nut, 0.1 to 0.3 part of yeast selenium, 18 to 20 parts of fish, 19 to 23 dried shrimp, 1 to 3 parts of dark soy sauce, 2 to 5 parts of peanut oil, 2 to 4 parts of peanut butter, 15 to 17 parts of litchi, 14 to 16 parts of celery, 0.1 to 0.3 part of radix bupleuri, 0.6 to 1.1 parts of Chinese wolfberry, 0.2 to 0.4 part of citron fruit, 7 to 9 parts of lotus leaves, 1 to 3 parts of forestry greenstar root, 3 to 6 parts of a feed attractant, and moderate amount of water. The crab feed rich in organic selenium provided by the invention has the benefits that the selenium content is stable and controllable and can be adjusted at will within a certain range, the growth of crabs is facilitated, the disease resistance of crabs is improved, the crab meat quality is improved, the crab quality and the survival rate are improved.