Abstract: The occurrence of fire often leads to the damage and deterioration of the micro-meso-structure of concrete materials, which is reflected in the decomposition of hydrates, the coarsening of pore structure, thermal cracking, and the cracking induced by the increase of water vapor pressure, which in turn lead to the decline of the macroscopic mechanical properties and durability of materials. The meso-regulatory function of the lightweight, high-strength, internally porous, and highly thermally stable glazed hollow beads (GHB) can improve the high-temperature resistance of concrete. In order to study the characteristics of the internal meso-scale structure and crack evolution of recycled aggregate thermal insulation concrete (RATIC) subjected to high temperature, the cube compressive strength test and CT test were firstly carried out on RATIC after high temperature. Then the RATIC meso-scale model was established based on the real structure by the improved image segmentation algorithm based on the adaptive threshold method and the regional growth method (IISA). The process of initiation, development and coalescence of internal microcracks in RATIC with different GHB and recycled coarse aggregate (RCA) contents with temperature change were studied. Furthermore, the failure patterns of RATIC under simulated conditions and CT re-sults were analyzed by contrast, which show that GHB can significantly block the extension of cracks, provide a release channel for vapor pressure, alleviate cracks in the mortar area and pore boundaries, slow down the spread of heat in the concrete. It has a positive effect on improving the heat-induced damage resistance of concrete.