Abstract: The standard test method ASTM D 5470-2006 for thermal transmission properties of thermally conductive electrical insulation materials was introduced,and several measures to improve the measuring accuracy were discussed. It became possible that the thermally conductive interfacial materials produced by different factories could be compared by applying the standard test method. In addition,it was a great help for thermal design engineers of electronic products to select better thermally conductive electrical insulation interfacial materials.