Unbound aggregates are widely used in road engineering. In order to understand the mechanical properties of unbound aggregates, a review of the mechanical properties of unbound aggregates is conducted based on domestic and international research. Firstly, the research status of deformation performance of unbound aggregates for road is introduced, including shear deformation, dynamic resilient modulus and permanent deformation. Secondly, the anisotropy behavior of unbound aggregates is summarized and analyzed from two aspects, such as test method and evolution law characterization. Finally, the important factors influencing the mechanical behavior of unbound aggregates are summarized, and reviewed in terms of physical properties of aggregates, particle structure characteristics and external stress state. The analysis shows that: The mechanical properties of unbound aggregates are closely related to particle properties, structural characteristics and stress state, and are characterized by significant anisotropy. In the future, further research can be carried out from the aspects of rebound modulus calculation method, performance anisotropy parameter calculation method and dynamic stress response analysis.