As a core component of the fuel cell membrane electrode assembly, the Gas Diffusion Layer (GDL) exerts a direct influence on the power density, durability, and cost of the cell. Carbon fiber and carbon paper constitute the foundation of the GDL. This review systematically examines recent research progress in carbon fibers and carbon paper, encompassing aspects such as the material systems of carbon fibers and the fabrication processes of carbon paper. Furthermore, it analyzes the performance of these materials in practical Proton Exchange Membrane Fuel Cell (PEMFC) applications, and explores their specific impacts on battery power density, durability, and cost. Finally, the study summarizes current critical technical bottlenecks and future development trends, aiming to provide theoretical guidance and technical references for the research, development, and industrial production of high-performance GDLs.