As one of the core components of flexible electronics, flexible carbon fiber-based sensors exhibit broad application prospects in medical diagnosis, sports health, human-computer interaction and other fields by virtue of their excellent electrical conductivity, mechanical flexibility, chemical stability and biocompatibility. This paper systematically reviews the latest research progress of flexible carbon fiber sensors in healthcare monitoring. Focusing on the quantum tunneling effect and impurity scattering effect, we conduct an in-depth analysis of their stress and temperature dual sensing mechanisms, and reveal the spatial orthogonality between the radial piezoresistance and axial thermal resistance of carbon fiber beams. This unique characteristic endows a single carbon fiber beam with pressure-temperature dual-mode sensing capability, which provides crucial technical support for the miniaturization and integration of sensors. Combined with innovative structural design strategies (e.g., cross structure, H-type structure, corrugated structure), we systematically summarize the performance optimization paths and research achievements of such sensors in key parameters including sensitivity, stability and linearity. Furthermore, we elaborate on the innovative applications and practical effects of flexible carbon fiber sensors in multiple related fields: in medical diagnosis, they realize the digitalization of traditional Chinese medicine (TCM) pulse diagnosis, quantitative monitoring of tongue pressure for swallowing function assessment, accurate detection of core body temperature and integrated monitoring of multi-modal physiological signals; in sports health, they enable multi-scenario respiratory monitoring (including underwater monitoring), plantar pressure-based gait analysis and synergistic monitoring of joint-muscle movement; in human-computer interaction, they provide technical support for tactile perception of electronic skin, human motion capture and intelligent bionic interaction. Finally, we dissect the key challenges faced by flexible carbon fiber sensors in the industrialization of preparation processes and the optimization of comprehensive performance and environmental adaptability. Combined with interdisciplinary technologies such as artificial intelligence and machine learning, we prospect their future development directions and application potential in personalized medicine, intelligent rehabilitation, digital health management and other emerging fields. This review provides a valuable reference for the interdisciplinary integration and innovative development of flexible electronics, intelligent wearable devices and healthcare monitoring technologies.