Calcination behaviors play an important role in Fischer-Tropsch (FT) performance over a slurry iron-manganese catalyst. The present study was undertaken to investigate the effects of calcination behaviors (calcination temperature, heating rate and calcination atmosphere) on the textural properties, reduction/carburization behavior, bulk phase structure and FT synthesis performances over precipitated Fe-Mn catalysts. N-2 physisorption, X-ray photoelectron spectroscopy (XPS), H-2 thermal gravimetric analysis (TGA) and Mossbauer effect spectroscopy (MES) were used to characterize the catalyst. It is found that increasing calcination temperature and heating rate lead to low surface area and high enrichment of Mn on the catalyst surface. High calcination temperature also increased the crystallite size of alpha-Fe2O3 and suppressed the reduction/carburization of the catalysts in H-2 and syngas. Low calcination temperature and low heating rate promoted the further carburization of the catalyst and increased the activity during FT process. High calcination temperature and low heating rate restrained the formation of CH4, increases C5+ selectivity and improved the selectivity to light olefins. In addition, calcination in argon could improve the carburization and increase FT activity of the catalyst. The present iron-manganese catalyst with lower calcination temperature, lower heating rate and calcined in argon is optimized for its FT performances.