Abstract: Metamaterials have attracted worldwide attention because their physical properties can be designed to be beyond natural materials. Generally, the performance of metamaterials depends on the design of structural units and the properties of the material systems. Therefore, fin-ding the appropriate materials and optimizing the structural units are two main ways to improve the performance of metamaterial. With the gradual improvement of material system research, how to optimize the design of structural units effectively has become the key to improve the perfor-mance of metamaterials. Traditional metamaterials has been limited a lot by their drawbacks such as narrow frequency band, simple units' structures and poor behavior, therefore, it is urgent to propose a novel design strategy. Fractal geometry becomes the ideal solution due to its unique geometric properties such as self-similarity, cross-scale symmetry and non-integer dimension. Recently, the design concept centered on fractal structure formed gradually and has been applied to the design of metamaterials. Fractal geometry has been widely used in the fields of electromagnetic metamaterials, acoustic metamaterials, mechanical metamaterials and so on and the advantages brought by fractal structures have already been manifested. The introduction of the fractal structure not only achieves the goals such as broadband, miniaturization and integration, but also significantly improves the performance of the metamaterials. The application of fractal geometry shows great potential. This review summarized the current status of the design and application of fractal metamaterials in different fields. First, we introduced the concept of fractal geometry. Then, we analyzed the advantages and contributions of fractal metamaterials in different application fields by examples and summarized common synthesis methods of fractal metamaterials. Finally, we prospected the main challenges of fractal metamaterials and their development directions in the future.