Triboelectric nanogenerator (TENG), a rapidly growing technology that converts mechanical energy into electrical energy, has been advancing progress in energy harvesting and self-powered sensing. However, a critical challenge for the practical implementation of TENG is the difficulty in achieving high output performance, which is closely related to the high conversion dissipation from mechanical energy to electrical energy. Leveraging the biological structural traits honed through evolution to guide the design of TENG components has emerged as a promising approach to enhance the output performance of TENG. This review first describes the working principle, structural composition, and working mode of TENG, and lays a theoretical foundation for the bionic structural design of TENG components aimed at improving output performance. The complete process of converting mechanical energy into electrical energy is examined, with a focus on recent advances in bionic structures that enhance the performance of key TENG components, including front-end energy collection mechanisms, mechanical energy transfer components, friction layers, electrodes, and power-management strategies. The mechanisms by which the bionic structural design of these components affects the output performance of TENG are carefully revealed, and their advantages are highlighted as well. Finally, the main challenges of biostructure-inspired TENGs for practical applications are highlighted, and the corresponding potential solutions are discussed, providing valuable insights for future development and innovation.