The depolymerization of ehitosan by papain was studied. By determining the concentration of reducing sugar and viscosity in ehitosan solution, the effects on the efficiency of catalytic degradation of ehitosan by papain were investigated. The results showed that the optimal conditions for degradation of Chitosan with papain were ehitosan with 85.7% DD (deaeetylation degree),ehitosan eoneentration 0.5%, pH4.0, reaetion temperature 40℃, papain: ehitason = 1: 10 ;papain degraded quite quickly in initial reaction, the viscosity deerease per...