Abstract: Supported solid base catalyst KF/CaO/carclazyte for biodiesel preparation was prepared by co-mixture impregnation technology. Effects of catalyst preparation conditions on catalytic activities were studied. The structure and properties of the catalyst were characterized by SEM，TEM and BET. The optimal conditions to prepare catalyst are：mass ratio of carclazyte to CaO is 3∶7，KF loading is 20%，calcination temperature is 873 K，calcination time is 4 h. Thus prepared catalyst brings about more than 96% biodiesel yield from sapium sebferum seed oils. The catalyst characterization showed that the catalyst has a multiporous netlike structure with a particulate diameter of 30－100nm，an average pore size of 43 nm and a specific surface area of 113.9 m2/g.