The invention relates to a Chinese herbal medicine compound feed additive suitable for fattening pigs and a preparation method of the Chinese herbal medicine compound feed additive. The compound feed additive comprises 15-20 parts of a Chinese herbal medicine composition, 1-3 parts of amino acid, 1-3 parts of compound probiotics, 0.5-2 parts of an enzyme preparation, 1-3 parts of trace elements and 18-29 parts of wheat bran. The Chinese herbal medicine composition comprises 10-15 parts of astragalus membranaceus, 0.5-2 parts of ginseng, 10-15 parts of eucommia ulmoides, 1-5 parts of medlar, 10-15 parts of honeysuckle flowers, 2-5 parts of cortex fraxini, 0.5-2 parts of codonopsis pilosula, 4-8 parts of fermented soybean, 2-5 parts of burdock, 10-15 parts of epimedium, 5-15 parts of acanthopanax roots, 10-13 parts of purslane, 0.5-1 part of mint, 10-20 parts of pericarpium citri reticulatae, 1-5 parts of scutellaria baicalensis, 10-15 parts of schizonepeta and 5-10 parts of liquorice roots. The Chinese herbal medicine compound feed additive solves the problems of high morbidity, slow growth speed and high feed-gain ratio of the fattening pigs, and solves the problems of abuse of antibacterial drugs and drug residues.