The invention discloses a fish feed additive for improving activity of digestive enzymes. The fish feed additive is prepared from the following raw materials: 30-40 parts of rapeseeds, 30-35 parts of highland barley, 10-13 parts of lotus seeds, 20-24 parts of okra, 7-12 parts of fresh ginger, 20-25 parts of potatoes, 7-9 parts of Chinese prickly ash, 15-20 parts of fresh peach leaves, 3-4 parts of white vinegar, 4-5 parts of baijiu, 5-6 parts of white sugar, an appropriate quantity of lactic acid bacteria, an appropriate amount of bacillus subtilis, an appropriate amount of xylooligosaccharide and an appropriate amount of water. The Chinese prickly ash is treated at a low temperature, so that the smell of burnt food can be avoided from appearing, and Chinese prickly ash squeezing liquid after powder injection has the effects of resisting bacteria, diminishing inflammation, promoting appetite, and adjusting internal lipid metabolism; the fresh peach leaves have the efficacies of clearing heat and removing toxicity; the baijiu can enable effective components of the peach leaves to dissolve; the white vinegar can remove toxicity and restrain bacterial reproduction; the fresh ginger has the effects of promoting digestion liquid to secrete, resisting oxidation resistance, resisting tumors, resisting inflammation, resisting microorganisms and the like. After being fermented with the bacillus subtilis, dregs can promote beneficial anaerobic bacteria to grow, so that the immunity is improved.