The invention discloses a method for preparing polishing powder for onyx polishing, which is characterized in that the method has the following process steps: in the reactor, add according to the following composition mass percentage concentration, lead powder: 5-8% , compound: 80~88%, tin oxide: 5~13%, the sum of each component is 100%, turn on the grinder, grind at a speed of 500 rpm for 30~60min, and obtain agate polishing powder, in which the compound Contains nano aluminum nitride, aluminum oxide, zirconium oxide, iron oxide, cobalt oxide. The preparation process is simple, the conditions are easy to control, the production cost is low, and the industrial production is easy. In the polishing process, it has good powder polishing effect, high gloss, no scratches, high flatness, and less powder consumption.