Chitosan supported with Iodine was synthesized at room temperature and the structure was characterized by IR, XRD, and TGA. Ketalization of cyclohexanone and 1,2-propanediol catalyzed by chitosan supported with iodine was studied. The effect of reaction time, the ratio of alcohol and ketone, catalyst amount, and the volume of water-carrying agent on the yield of cyclohexanone 1,2-propylene ketal were investigated. The results show that the suitable condition for the reaction are as follows: the amount of cyclohexanone is 0.1 mol, the molar ratio of 1,2-propanediol and cyclohexanone is 1.3, the amount of catalyst is 0.4 g, the volume of cyclohexane used as the wate-carrying agent is 8 mL, reaction time is 60 min. The ketal yield is up to 96.3%. The catalyst could be reused five times without significant declining of catalytic activity.