Biomass porous carbon possesses broad application prospects in the field of energy storage. However, soft biomass materials with high cellulose content and orders structure usually represent low mechanical strength, which leads to unstable pore structure of prepared porous carbon and even prone to collapse, thus reducing the quality and stability of carbon. Herein, a simple molecular reconstruction method is proposed to effectively re-construct 3D disordered ramie precursors (DRPs) by regulating the chemical interaction of hydrogen bonds. Benefiting from high mechanical strength and high density of DRPs, the highly stable porous ramie carbon (PRC) can display a higher specific surface area of 2404.36 m2 g?1 than that of ordinary ramie carbon (2142.25 m2 g?1). Moreover, this PRC-based supercapacitor delivers a high specific capacitance of 39.35 F g?1 at 1 A g?1 and an excellent capacity retention rate of 89.5% at 40 A g?1 in 1 M Et4NBF4/AN. Attractively, the evolution process of ion adsorption during the charge–discharge process has been uncovered by using in situ electrochemical infrared spectroscopy, confirming the excellent structural stability of PRC. This work provides new insights into preparing biomass precursors with high strength derived from soft biomass materials, greatly promoting the application of soft biomass materials in commercial activated carbon.