The invention provides a functional preparation regulating health of gastrointestinal tracts of people and animals. The functional preparation comprises the following components in parts by weight: 20-80 parts of a plant composition, and 20-80 parts of microorganisms, wherein the plant composition comprises the following components in parts by weight: 1-10 parts of horseradish tree leaves, 1-10 parts of guava leaves, 1-10 parts of eucommia ulmoides leaves, 5-20 parts of poria cocos, 2-20 parts of dried orange peel, 1-20 parts of radix astragali, 1-15 parts of fructus gardeniae, 1-10 parts of calystegia hederacea, 5-20 parts of radish seeds, 1-10 parts of bighead atractylodes rhizomes, 5-20 parts of haws, 5-30 parts of chicory and 5-30 parts of helianthus tuberosus tubers, stems or leaves,and the microorganisms comprise one or more of bacillus subtilis, natto bacillus, saccharomyces cerivisiae, S.boulardii, lactobacillus acidophilus, Lactobacillus casei, lactobacillus plantarum, bifidobacterium lactis, bulgarian bacillus, streptococcus thermophilus, and clostridium butyricum. The functional preparation is prepared by fermenting the plant composition with the microorganisms. The products provided by the invention are good in flavor, good in effect, and stable in quality, are suitable for daily health care of people or animals, and have positive effects in the respects of maintaining the stomach and intestinal tracts of people or animals healthy, improving immunity and the like.