Abstract: An anodization process was used to produce an insulating layer of anodic film for ideal Insulated Metal Substrates （IMS）. Electronic Speckle Pattern Interferometry was utilized to measurethe cracking temperature of anodic films in thermal shock experiments. The effect of pre-treatment process of aluminum plates on the thermal shock resistivity of anodic films was studied, and Scanning Electron Microscope （SEM） was used to observe where cracks originated. The analysis indicates thatthe unevenness of Al surface before anodization could cause the formation of a kind of interface where the porosity is higher in the anodic film, and cracks are easy to generate at the interfaces during theprocess of thermal shock.