In view of peeling-off of coating surface and cracking between layers caused by CMAS (CaO-MgO-Al2O3-SiO2) corrosion, the corrosion mechanism of CMAS for thermal barrier coating was discussed. Due to some disadvantages of the currently used methods, it is urgent to study new material systems and related processes to resist CMAS corrosion. Crack failure, as the main failure mode of thermal barrier coating, can be effectively improved by reducing the oxidation rate of the oxide layer and increasing the toughness of the ceramic layer. Based on analysis on complexity of the coating structure, it could be found that the coating needs to be expressed from three perspectives: macroscopic, mesoscopic and microscopic. Therefore, the use of cross-scale theory had important significance for the analysis of coating structure and other issues. For this purpose, it was pointed out that a meso-toughening thermal barrier coating should be developed to prevent CMAS corrosion and coating cracking. The crack analysis for this kind of coating should also be carried out through cross scale. The results are important for enriching of toughening methods and enhancement of anti-corrosion properties of thermal barrier coatings, which can also ensure safe service of thermal barrier coatings and even that of aero engines.