Abstract: A series of spherical ironbased (Fe/Mn/K) catalysts were prepared by the combination of coprecipitation and spray drying method; the influences of incorporation manner of Mn promoter on their crystallite structure, reduction and carburization behaviors and performances in FischerTropsch synthesis were investigated though H2 differential thermo gravimetric analysis (H2-DTG), CO temperatureprogrammed reduction (CO-TPR), Mossbauer spectroscopy as well as catalytic tests. The catalysts were evaluated in a slurry reactor under the industrially relevant reaction conditions of 250℃, 1.5MPa, H2/CO = 0.67 and a space velocity of 2.0L/gcat-h. The results illustrated that the addition of precipitated Mn brings on stronger Fe-Mn interaction than other incorporation manners; this may suppress the reduction and carburization of the catalyst, decrease the catalytic activity but enhance the catalytic stability. The addition of partial precipitated and binder Mn promotes the reduction and carburization of the catalyst, improves the catalytic activity but speeds up the catalyst deactivation. Compared with the precipitated Mnpromoted catalyst, the addition of partial precipitated and binder Mn can enhance the selectivity of heavy hydrocarbons and olefins and restrain the formation of oxygenates.