Abstract: Mélange is a rock mass containing foreign or in situ blocks in a fine-grained fractured matrix and is often characterized by diverse material composition, complex geological structure and widely varying engineering properties. The internal heterogeneity and spatial variability of the mélange in lithological composition and mechanical properties would have a significant influence on siting and stability of the engineering project. Nowadays, engineering and geological hazards occur frequently in mélange areas. In order to satisfy the demand for rapid and safe construction of engineering projects in this region, the engineering mechanical properties of mélange need to be clarified urgently. This paper systematically reviews the literature on the mechanical properties of mélange. The non-homogeneous properties of the mélange are used as the entry point for this paper. First, the reasons for the formation of inhomogeneity of mélange are summarized. On this basis, the current classification methods of mélange are generalized. Second, the current methods describing the inhomogeneous properties of mélange are analyzed. The influencing factors and prediction methods on inhomogeneous mechanical properties of mélange rocks are also discussed. Finally, the mechanical properties of mélange rock masses in an engineering context are summarized. In the future studies need to be focused on the following three areas: quantitative classification methods hased on the mechanical properties of mélange, the mechanics of mélange under the influence of multiple factors, and the relationship between the geometric distribution and mechanical properties of mélange at a engineering scale. This paper can be useful for clarifying the mechanical properties of mélange rocks and reducing the engineering risks in this type of area.