Abstract: With the development of centrifuge materials, the properties of the matrix of epoxy resin composites make a higher demand. The preparation process and mechanical properties of the epoxy resin/nano-Al₂O₃ polymer were investigated. With the treatment of silicone coupling on the surface of nano-Al₂O₃ particles and the action of mechanical decentralization and ultrasonic wave, the particles were dispersed in the matrix of epoxy resin. The result of the TEM analyses shows that the nano-Al₂O₃ particles treatmented can be uniformly dispersed in the matrix of epoxy resin. The effects of the pH value of the solution and ultrasonic time to the modified nanoparticles were studied, and the result shows that the optimum pH value is 4-5 and ultrasonic time is 20 min.