To improve chitosan’s solubility in water,citric-chitosan was successfully synthesized for the first time in the mild condition with chitosan and citric acid as raw material and ethanol as reaction medium,and the process parameters were optimized: the molar ratio of citric acid to chitosan is 2∶1,the reaction temperature is 20 ℃ and the reaction time is 0.5 h.IR analysis result shows that the carboxylation reaction has occurred between citric acid and chitosan and citric acid has been successfully grafted on chitosan.In addition,the result of solubility in water shows that the citric chitosan’s solubility in water has increased a lot compared with that of the former chitosan.