A series of KF / ૪ -Al2O3 catalysts were prepared and used for glycerol polymerization. The effect of the calcination temperature and KF loading on the degree of polymerization of the polyglycerin were investigated. The structure and performance of catalysts were characterized by XRD ,Hammett indicator method, TG-DTA，CO2-TPD，BET methods. The results showed that under the conditions: the calcination temperature was 600°C, the KF content was 40%, the degree of polymerization of the polyglycerin was up to 6.21. Catalytic activity depended on the amount of K3AlF6 existed on the surface of catalyst.