In order to realize the high-value utilization of waste lignocellulose, bamboo powder was used as raw material, and the deep eutectic solvent (DES) composed of choline chloride (ChCl)/lactic acid (LA) was used to separate the components of bamboo powder. The lignin and cellulose were reconstructed by a simple hot-pressing method to prepare lignocellulosic board. In this paper, the effects of the components of DES, the amount of ferric chloride, reaction temperature and reaction time on the separation of lignocellulosic components were investigated. The structure and properties of DES-separated lignin (DESL) and cellulose (DESC), DES/FeCl3-separated lignin (DESL-FeCl3) and cellulose (DESC-FeCl3), and lignin fiberboards were analyzed by infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), scanning electron microscope (SEM), Zeta potential tester, and universal testing machine. The results showed that the optimum process conditions were choline chloride and lactic acid with a molar ratio of 1:2, FeCl3 addition amount of 2%, reaction temperature of 140 ℃, and reaction time of 6 h. The yields of lignin and cellulose under these conditions were 85.57% and 48.4%, respectively. The phenolic hydroxyl number and Zeta potential of the extracted lignin were 12.86 mmol/L and -32.26 mV, respectively, and the particle size was small. The extracted cellulose had more active sites, which were favorable for the molecular reconstruction and interfacial bonding with lignin. After five cycles of recycling, DES still had good separation performance for lignocellulose. The water stability and mechanical properties of the prepared lignocellulosic board had been improved, water contact angle reached to 58.6°, and its tensile strength increased from 8.4 MPa to 53.1 MPa, which had the potential to replace petroleum-based plastics.