A metoprolol fumarate sustained-release tablet and a preparation method thereof. The sustained-release tablet with a total amount of 1000 tablets and an administration interval of 24 h is prepared by the following components: 95 g of metoprolol fumarate used as a main drug; 100-300 g of hydroxypropyl methyl cellulose used as a skeletal material; 30-50 g of ethyl cellulose or low-permeability acrylic resin used as a retarding agent; 100-300 g of 85% ethanol used as a wetting agent; 2.68 g-4.02 g of magnesium stearate used as a lubricant, and 5.025-8.375 g of talcum powder used as a flow aid. The main drug is well mixed firstly with the retarding agent and then with the skeletal material; a soft material and granules are prepared by he wetting agent; the granules are dried and sized; the lubricant and the flow aid are added for tabletting; when the tablet is qualified after examination, the metoprolol fumarate sustained-release tablet is obtained. After administration, the drug is released slowly; not only the everyday administration frequency is decreased, which is convenient for drug administration of clinical doctors and patients, but also the blood concentration of the drug is stable; no peak-valley phenomenon is generated; the toxic and side effect is decreased to a lowest level; and the patient compliance is good.