The thiolated chitosan (CS-NAC) was synthesized by grafting N-acetyl-L-cysteine (NAC) onto chitosan chain and the structure was characterized by 1HNMR and FTIR. The content of thiol group in CS-NAC was determined to be 275.8μmol/g by Ellman’s method. The disulfide bond crosslinked CS-NAC hydrogel was prepared by oxidation coupling of thiol with oxygen. The stable hydrogel was obtained in the CS-NAC concentration range of 1.5wt% to 3.0wt%. The swelling ratio of CS-NAC hydrogel decreased from 45.5 to 31.2 and the mesh size (ξ) diminished from 340nm to 242nm with increasing the concentration of CS-NAC from 1.5wt% to 3.0wt%. The redox-responsive degradation of CS-NCA hydrogel was observed. About 80% hydrogel was degraded in 10mmol/L dithiothreitol (DTT) solution within 400min, and complete degradation was observed in 50mmol/L L-cysteine (L-Cys) solution. Bovine serum albumin (BSA) was used as model protein and encapsulated into the CS-NAC hydrogel during the oxidation crosslinking reaction. Redox-responsive release of BSA in vitro from CS-NAC hydrogel was obtained. More than 80% of encapsulated BSA was released from the hydrogel in 10mmol/L DTT solution within 30 h, while only 58% of BSA was released from the hydrogels in PBS. The release kinetics of BSA in 10mmol/L DTT solution is closed to first order and the encapsulated protein was released via a typical Fickian diffusion-controlled form from the CS-NAC hydrogel.