In recent years, with the development and popularization of Internet and artificial intelligence, the flexible pressure sensor with light, convenience and excellent electronic performance, as the core device of wearable electronic equipment, has a increasingly broad market. Flexible pressure sensors have attracted extensive attention in electronic skin, motion detection, medical monitoring and man-machine interface because of its flexibility, folding and excellent sensing performance. The construction of micro-nano structures is the key to improve the sensitivity and sensing performance of pressure sensors. Based on this, the sensing mechanism (piezoresistive, capacitive, piezoelectric, triboelectric) and key performance parameters (sensitivity, pressure response range, detection limit, response/recovery time, stability of circulation and linearity, etc.) of the high-sensitivity pressure sensors were summarized. Then, research progress of flexible pressure sensors using substrates to construct surface micro-nano structures (micro-convex structure, bramble structure and fold structure) and using conductive materials to construct micro-nano structures (micro-sphere structure, urchin structure and cellular structure) were compared and concluded. Furthermore, the application status of high-sensitivity flexible pressure sensors based on micro-nano structure in pulse detection, electronic skin, motion detection and man-machine interface was concluded. Finally, from the perspective of future application, the challenges and development direction of high sensitivity flexible pressure sensor are summarized.