Abstract: Microstructuring is one of the important techniques to improve the performance of flexible pressure sensors. In this paper, a method for designing and fabricating hierarchical microstructures based on micro/nano fibers was proposed. First, a sacrificial mold with hierarchical microstructures was prepared by integrating near-field direct writing and fused deposition modeling. Carbon nanotubes (CNTs) were doped into polydimethylsiloxane (PDMS) as the dielectric layer material for the flexible sensor. The CNTs/PDMS flexible dielectric layer with hierarchical microstructures was then prepared by sacrificial template method. Furthermore, the effect of design parameters of hierarchical microstructures on the sensing performance was studied. The experimental results show that the designed microstructures can significantly enhance the output electrical performance of the flexible sensor. Among them, the hierarchical microstructure with a height of 1.3 mm and a spacing of 1.5 mm exhibits the best output electrical performance under a pressure load of 14 N at a frequency of 3 Hz. In addition, the fabricated sensor exhibits good stability and durability after 20000 cycles of testing. Finally, a flexible pressure sensing insole was designed for observing the distribution of foot pressure and gait detection, which demonstrates good sensitivity and stability. This study provides a new approach for low-cost and rapid fabrication of hierarchical microstructures and serves as a reference for the development of high-performance flexible pressure sensors.