[Objective]The best combination condition of chitosan and -Fe2+ to prepare chitosan ferrous composition was studied to provide theoretical references for reducing CO in the mainstream smoke of cigarette. [ Method ]The initial concentration of the ferrous, the pH value of system, reaction time and the dosage of chitosan were devised to investigate their effects on the quality of chitosan ferrous composition so that the optimum conditions could be identified. [Result] When the initial concentration of the ferrous was 15 mg/mL, the pH value of system was 2.5-3.0, stirring duration 1 hour, reaction time 4 hours and the usage of chitosan 0.1 g, the maximum quantity of chitosan ferrous composition could reach 523 mg/g. [Conclusion]It is viable to use chitosan ferrous composition to cut CO in the smoke.