Textiles are fabrics of daily life, relying on fibers as their core components. Despite growing research on fast fashion's environmental impacts, systematic quantification of textile fiber flows and stocks remains limited. This study applies dynamic material flow analysis (dMFA) to track flows and stocks of nine types of fibers in China (1978-2022), the global leader in fiber and textile production. The findings indicate a marked transformation in textile production and consumption structure in China through time. China recorded a cumulative production of 1.09 Gt fibers and net export of 437 Mt fibers and textiles over the past 45 years. By 2022, 347 Mt fibers remained as stocks. Current textile waste recovery rate stands at 17 %, predominantly downcycling. Achieving closed-loop fiber-to-fiber recycling demands cross-value-chain collaboration. This quantitative assessment provides the foundation for understanding the complexity of the textile fiber system and paves the way for creating a circular textile fiber economy.