First,transparent SiO2/silicone resin was prepared by means of the sol-gel method,with tetraethoxysilane and organosiloxane as the raw materials.Then,polyester/SiO2/silicone hardcoat composite films were synthesized on polycarbonate（PC） via the condensation between SiO2/silicone resin and polyester.Finally,the effect of SiO2/silicone resin-to-polyester ratio on the properties of the composite coating was discussed,and the structure and properties of the composite coating were characterized by means of FT-IR,TGA,AFM,SEM,UV spectroscopy and XRD,etc.The results show that the composite with structure is obtained due to the co-condensation between the ethoxy groups in SiO2/silicone resin and the hydroxyl groups in polyester,that the composite coating which is an SiO2/silicone resin mass fraction ranging from 75% to 83% and a storage period of more than ten months,possesses good stability,and that the composite film after the thermal curing,which is smooth and amorphous,improves the transparency of PC sheet,with an adhesion strength to PC sheet of 0 grade and a pencil hardness of 2H.Moreover,it is indicated that the composite film is of excellent thermal stability gradually increasing with the SiO2/silicone resin dosage.