Abstract: Two spherical iron-based catalysts (Fe/Cu/K/SiO2 and Fe/Cu/K/Al2O3) were prepared by the combination of coprecipitation and spray drying method for the application of slurry Fischer-Tropsch synthesis (FTS). The effects of SiO2 and Al2O3 on the reduction and the carburization behaviors of iron-based catalysts were studied using temperature-programmed desorption (TPD) in H2 and CO, isothermal reduction in syngas, and Mssbauer-effect spectroscopy (MES). The results indicate that SiO2 suppresses the H2 adsorption, facilitates the CO adsorption, and the carburization as compared with Al2O3. The FTS performances of the catalysts were evaluated in a slurry reactor under the industrial relevant reaction conditions of 260℃, 1.5MPa, H2/CO = 0.67, and a space velocity of 2000h-1. This indicates that SiO2-supported catalyst has higher FTS activity, higher water-gas shift reaction (WGS) reactivity, and higher selectivities to heavy hydrocarbons. Furthermore, the run stability of Al2O3 supported, iron-based catalyst is better than SiO2 supported catalyst.