The invention discloses a preparation method for an epoxy resin binding agent diamond grinding tool with high polishing performance. A working layer is mainly prepared from a diamond grinding material, an auxiliary grinding material, epoxy resin, a curing agent, rare earth polishing powder, filler and a dilution agent. The preparation method comprises the steps of uniformly and mechanically mixing 5-20 parts of the diamond grinding material, 5-20 parts of the auxiliary grinding material, 5-25 parts of the rare earth polishing powder and 5-40 parts of the filler to obtain a first mixture, then uniformly mixing and stirring the first mixture with 20-40 parts of the epoxy resin, 7-15 parts of the curing agent and 0.5-10 parts of the dilution agent to obtain a final mixture, injecting the mixture with flowability into a plastic mold in a pouring manner, and curing the mixture to obtain the epoxy resin binding agent diamond grinding tool with high polishing performance. The materials are in percentage by mass. Compared with the conventional hot pressing molding method, the preparation method has the advantages that the technology is simple, the energy is saved, and the emission is reduced; the pollution, which is caused by solid dust, to the environment is reduced, and the production speed is high; compared with the conventional product in the foreign country, the epoxy resin binding agent diamond grinding tool has the advantages of good polishing effect, high polishing efficiency, few air hole defects of the grinding tool and the like.