Concrete has a high degree of heterogeneity and a complex porous structure, so to accurately study the performance evolution mechanism of concrete, multi-scale research should be carried out. A three-phase meso-model of concrete is constructed based on the method of randomly generating particles. A mesomacro connection framework is built, and the accuracy of the fixed hygro-thermo-chemical model at the meso-scale is verified through comparing its outcomes with experimental data and macroscopic results. The hygro-thermo-chemical behaviours of early-age concrete at the meso-scale are studied under adiabatic -sealed, radiating-sealed and adiabatic-drying conditions, by considering the cooling effect of the aggregate, low diffusivity of the aggregate, high diffusivity of the interface transition layer and concrete gradation. Additionally, distribution and evolution of several eigenvalues, such as the relative humidity, are obtained. (C) 2018 Elsevier Ltd. All rights reserved.