The invention provides a novel potassium citrate sustained release tablet and a preparation method thereof, the preparation method comprises the steps of crushing, weighing raw materials, granulating, mixing and tabletting. The potassium citrate sustained release tablet comprises the following components: potassium citrate, a lipid material (monoglyceride stearate, glycerol distearates, glyceryl behenate, glyceryl palmitate-stearate, glycerol trilaurate, neodecanoic acid glyceride, stearic acid, palmitic acid, beeswax), lactose and microcrystalline cellulose. The potassium citrate sustained release tablet is prepared by the components by weight percentage: 1-50% of potassium citrate, 10-50% of lipid material, 10-70% of filler, 0-60% of wetting agent, 0.1-5% of adhesive and 0.1-2% of antitackiness agent. The potassium citrate sustained release tablet has the advantages of the quality is good, medicine release is alleviated, and biology utilization degree is increased.