By combination of numerical simulation and experiment， a three-dimensional spherical random aggregate model of concrete was established. The finite element software was used to analyse the temperature response and damage accumulation process. The simulation results were verified by the large temperature difference cycling test. The results show that with the increase of temperature difference cycling times， the thermal conductivity of concrete becomes worse and the temperature gradient increases. Large tensile stress is generated at the interface between aggregate and mortar， and the damage starts from the interface. The tensile stress increases in the heating process of each cycle， with the result that the damage gradually accumulate and expand from the interface to the matrix， and at last the damage area is connected. The simulation results of temperature response and static elastic modulus loss rate are in good agreement with the experimental values.