The rapid growth in energy consumption demands has spurred new requirements for energy harvesting technologies. Among these, the triboelectric nanogenerator (TENG) stands out as a promising sustainable energy collection device, garnering increasing attention for its efficient conversion of mechanical energy into electrical energy. This surge in interest has further fueled exploration into novel materials and fabrication techniques. In recent years, liquid metal (LM) with unique fluidity and conductivity has been developed as a triboelectric material. Liquid metal-based TENGs (LM-TENGs) possess remarkable advantages in terms of conductivity, flexibility, high stability, and functionality, demonstrating immense potential in performance. Herein, the latest progress of LM-based triboelectric materials and their TENGs are systematically summarized. Firstly, the development, characteristics, principles of improving TENGs performance, and design methods of LM-based triboelectric materials are introduced. Meanwhile, the design methods of LM-TENGs are comprehensively investigated, such as patterning, encapsulating, and blending. The applications and trends of LM-TENGs in energy harvesting, electronic textiles, electronic skins, and self-powered sensors are introduced in detail. Finally, key issues and challenges in this field are discussed, along with prospects for future development.