In this paper，nano-Al₂O₃ particles were dispersed into polyester resin bymechanical dispersion and ultrasonic dispersion processes to enhance the mechanicalproperties of water-based polyester resin. The effects of mechanical dispersion speed anddispersion mode on the performance of nano-Al2O3/polyester resin composite coating and the dispersion of nano-Al₂O₃ in polyester resin were investigated. The best dispersion process wasdetermined by studying the properties of the composite coating such as salt spray，sand washing resistance，hardness and wear resistance. The results showed that the nano-Al₂O₃ particles could form a homogeneous dispersion system under mechanical dispersion at 1 500 r/min，and the dispersion effect and stability of the coating would be further improved by ultrasonic dispersion，which could effectively reduce the agglomeration of nano-Al₂O₃ in water-based polyester resin and enhance the corrosion resistance of the composite coating
while improving its hardness and wear resistance.