The invention relates to a berberine hydrochloride sustained-release tablet and a preparation method thereof. The berberine hydrochloride sustained-release tablet mainly comprises 100-200 parts of berberine hydrochloride, 25-75 parts of a sustained-release material, 5-25 parts of a disintegrant, 5-25 parts of a coating agent and 54-170 parts of auxiliary materials. A pellet tableting technology isadopted to prepare the tablet, and drug-containing pellets are separated by buffer pellets, so that direct contact between coating films of the drug-containing pellets is avoided, and the coating films are not changed in the tableting process. The sustained-release effect of 12 h can be achieved in the gastrointestinal tract and is not influenced by gastric emptying, the bioavailability of the medicine is high, and the relative bioavailability is 273.2% of that of a common berberine hydrochloride tablet. Meanwhile, irritation or adverse reaction caused by local drug concentration can be reduced, and drug taking compliance of patients is improved.