In order to improve antithermal shock of anodic oxidation membrane on aluminum alloy for heat dissipation substrate of high-power integrated circuit, an organic/inorganic composite membrane on aluminum alloy was investigated through one-trip anodic oxidation. The microstructure, ingredient and performance of composite membrane was characterized through scanning electron microscope(SEM), Energy Dispersive Spectrometer(EDS), microscopic hardness meter, dielectric withstand test station and so on. The results indicated that the structure of composite membrane formed on aluminum alloy 6061 was multilayers piled up of bar-like pieces, which was definately different from traditional anodic oxidation membrane. The breakdown voltage and hardness were 1400V and 282 HV respectively, which were little lower than 1600V and 394HV of traditional anodic oxidation membrane. Composite membrane has a high resistivity in the order of 1014Ω×cm, which was equal to that of traditional anodic oxidation membrane. However, the antithermal shock properties of composite membrane were more excellent than traditional ones, its did not change after processing 10 cycles of heat/cool treatment. In contrast, the resistivity and configure of traditionals changed significantly. In conclusion, the composite membrane formed with one-trip anodic oxidation possessed good insulation, high antithermal shock, as well as breakdown voltage, which is potential for application as heat disspation substrate in high-power integrated circuit.