Calcium-silicate-hydrate (C-S-H) gel is the most important product of cement hydration and the only phase with the evolving microstructure in cement-based materials. Previously, extensive researches have adopted nanoindentation to investigate the mechanical properties of various C-S-H gels at mature ages, revealing two packing morphologies of C-S-H gels (i.e. loose-packed C-S-H and dense-packed C-S-H). However, the study on the early-age formed C-S-H gel is rare, resulting in the poor understanding on the evolution of the mechanical properties of C-S-H gel. The study adopts nanoindentation and dynamic modulus mapping to investigate the C-S-H gel formed by C₃S hydration and give an insight into the evolution of the elastic properties of C-S-H gel.