Cement-based materials are the most used construction and building materials in the world. This paper reviews the state-of-the-art of fractal geometry on cement-based materials. The porous structure of cement-based materials is extremely complicated and irregular, which is difficult to be described in terms of geometry. The fractal geometry is widely applied to investigate the pore structure of cement-based materials. In this work, the fractal characteristics of porous cement-based materials combined with the mathematical methods are discussed. Some direct and indirect methods for the evaluation of fractal dimensions are introduced, such as mercury intrusion porosimetry (MIP), nitrogen adsorption/desorption (NAD) and nuclear magnetic resonance (NMR). Some experimental results from different methods are compared to illustrate the advantages and disadvantages of these methods. Finally, correlations among fractal dimensions and properties of cement-based materials, such as permeability, diffusivity, strength and fluidity, are summarized. (C) 2020 Elsevier B.V. All rights reserved.