Concrete is a fundamental and key structural material for modern civil engineering construction. The development of modern engineering construction poses new challenges to the performance of concrete. Calcium-silicate-hydrate (C-S-H) is the most important product of cement hydration, which occupies about 70% of the hydration products. It is also the most important cementitious material in concrete. C-S-H plays a key role in cementing sands and coarse aggregates, and exerting the strength. At the microscale, C-S-H is a porous material with a complex microstructure. Therefore, the analysis and design of C-S-H micromechanical properties is essential for understanding and improving the macroscale mechanical properties of cement-based materials. It is also a fundamental scientific problem in the field of concrete research. This paper aims to introduce the micromechanical characterization method of concrete, the micromechanical theory of concrete, and the new findings obtained from the applications of micromechanics into concrete, and to forecast the application of concrete micromechanics in engineering construction.