In this work, using carboxyl-modified Fe₃O₄ nanoparticles as a photothermal agent, combining the chemical amide bond and intermolecular hydrogen bond crosslinking force, a photothermal hydrogel with enhanced mechanical properties was designed and prepared. Our results indicate that the carboxyl-modified Fe₃O₄ not only gave hydrogel photothermal properties, but also provided carboxyl sites for the formation of amide crosslinks with the amino group of carboxymethyl chitosan. Compared with carboxymethyl chitosans–acrylamide (CMCS–AM), the mechanical properties of carboxymethyl chitosans–Fe₃O₄–acrylamide (CMCS–Fe₃O₄–AM) have been significantly improved. In addition, adjusting the ratio of Fe₃O₄, CMCS, and AM can change the structural density, mechanical strength, and photothermal properties of the nano-composite hydrogel. The hydrogel also showed good drug loading and antibacterial properties. This research is of great significance to guide the design of new hydrogels with good mechanical properties, controllable crosslink density and photothermal properties.