Abstract: The effects of adding order of K on the textural properties, reduction behavior, phase transformation, surface basicity and slurry FischerTropsch synthesis (FTS) performances over the spherical Fe-Cu-K-SiO2 catalysts were studied by using N2 physical adsorption, H2 temperatureprogrammed reduction (TPR), CO2 temperatureprogrammed desorption (TPD), Mssbauer spectroscopy and Xray diffraction (XRD). The results indicated that adding order of K could affect the textural properties very slight. The catalysts with later addition of K have stronger surface basicity, which could inhibit the H2 reduction of Fe2O3→Fe3O4 but promote carburization of the catalyst. The catalysts with later addition of K show better reaction stability, higher FTS activity, lower CH4 selectivity and higher selectivity of olefin and heavy hydrocarbon. The results indicate that the later addition of K should be a better choice for Fe-Cu-K-SiO2 catalyst preparation.