The work aims to control interfacial electrical and thermal conductivity, and establish relevancy between thickness of micro-arc oxide film and its electrical and thermal conductivity by performing micro-arc oxidation to aluminum substrate for LED packaging use. Phase structure in micro-arc oxidation coatings of different thickness was characterized by XRD. Surface morphology of the coatings was observed using SEM. Electrical resistivity of the coatings was tested at different testing voltage with a high resistance meter. Thermal diffusivity of the coatings at different temperature was measured in laser flash method. The micro-arc oxidation coating was mainly composed of γ-Al2O3 phase. With the increase of coating thickness, phase structure of the coatings changed slightly while porous structure on surfaces of the coatings changed remarkably. Electrical resistivity of the coatings increased as the coating thickness increased. The resistivity increased by 4~8 times as the coating thickens ranged from 10 μm to 40 μm. The resistivity decreased as the testing voltage increased. The resistivity decreased by 1~2 orders of magnitude when the voltage ranged from 50 V to 100 V. Furthermore, fluctuation was present in the thermal diffusivity of micro-arc oxidation coatings as the coating thickness increased. Variation of the thermal diffusivity was 21.6~24.8 m2/s at the coating thickness of 10~40 μm. The diffusivity might decreased (by up to 8.9 m2/s) as the testing temperature increased. The 40 μm-thick micro-arc oxidation coating not only exhibits high electrical resistivity of 7.1×1012 Ω?cm, but also high thermal diffusivity of 98.0 m2/s, thus meeting the requirements of interfacial insulation and heat dissipation of LED aluminum substrate.