High-strength chitosan hydrogels (H-CS) were prepared without external crosslinker based on a LiOH/urea solvent system. The resultant H-CS hydrogels showed much better mechanical properties than conventional chitosan hydrogels (L-CS). Mechanical properties of H-CS can be tuned by adjusting the concentration of chitosan solution. SEM images of freeze-dried H-CS hydrogels displayed well-defined, interconnected, three-dimensional porous network structures that could greatly improve their mechanical properties. H-CS hydrogels fabricated in this study show great potential as a structural and functional material in the biomedical field.