The invention provides an LED ceramic baseplate and a preparation method thereof. The baseplate comprises the following components by weight percent: 60-70 percent of aluminium oxide, 0.2-0.5 percent of rare earth oxide, 10-30 percent of organic solvent, 0.2-1.2 percent of surface-active agent, 3.5-5.5 percent of adhesive, 2.5-7.2 percent of fluidizer and 2-5 percent of oxide additive. The preparation method comprises the following steps of: first, respectively and accurately weighing the components at respective weight percent, uniformly mixing and ball milling; next, performing vacuum defoamation and agitating; then, sequentially performing coating forming, hot-air drying, punching processing, vacuum encapsulation, pressing and cooling; finally, performing aging, low-temperature burnout, sintering and cooling. Due to the adoption of the method, the prepared ceramic baseplate is high in heat dissipation performance and surface finish, low in roughness, enhances light reflectivity, improves lighting effect, reduces light decay, and prolongs service life of an LED lamp.