The increasing accumulation of plastic waste has brought serious environmental issues. Biodegradable plastics are promising candidates to solve the problem but still remain a scientific challenge. Here, xylan plastic (XP) was fabricated by a strategy of double cross-linking through etherification combined with hot pressing. The mechanical properties, particularly the toughness of XP, were significantly enhanced by the incorporation of chemical and physical cross-linking domains. The tensile strength, toughness, and modulus of XP can reach up to 55 MPa, 2.2 MJ/m3, and 1.7 GPa, respectively, which are superior to most traditional plastics. Dynamic mechanical analysis (DMA) characterizations confirmed that XP is thermoplastic and can be hot formed. Additionally, the reversible hydrogen bond interaction between xylan chains could be simply regulated by water molecules, rendering XP readily transformed and repeatedly reprogrammed into versatile 2D/3D shapes. Moreover, XP showed a low thermal expansion coefficient and excellent optical properties. Cytotoxicity and degradability tests demonstrated that XP had excellent nontoxicity and can be biodegraded in 60 days. This work thus suggests an avenue for the scalable production of high-performance xylan-based plastics, in which the raw material comes from industrial wastes and exhibits great potential in response to plastic pollution.