Abstract: Two Al₂O₃-modified catalysts were prepared by urea hydrolysis method and precipitation disposition method respectively. Combined with N₂ adsorption, XRD, XPS and H₂-TPR, the effects of Al₂O₃ on the physico-chemical properties and catalytic properties for the Fischer-Tropsch synthesis were investigated. It was found that the metal-support interaction could be effectively strengthened for both catalysts. Consequently, the dispersion of the catalyst was enhanced and the Fischer-Tropsch synthesis activity was increased. The results also indicated that the modification of Co/SiC catalyst strongly depended on the preparation method. The highest CO conversion was observed on the catalyst prepared by urea hydrolysis method due to the superior dispersion and good reducibility. Besides, the catalytic stability was enhanced due to the stronger interaction between cobalt and Al₂O₃ prepared by precipitation disposition method.