Fischer-Tropsch synthesis (FTS) for the production of light olefin from syngas was investigated on K-Fe-Cu-Al catalysts. The catalysts were prepared by different methods, such as K impregnated over co-precipitated Fe-Cu-Al, K impregnated over sol-gel (pechini) synthesized Fe-Cu-Al, Fe-Cu-K impregnated on alumina and K impregnated over co-precipitated Fe-Cu in a slurry phase of Al2O3. Among four catalysts, K impregnated over Fe-Cu-Al prepared by sol-gel method has shown the best activity. A favorable pore size distribution and pore volume, manifested in a facile reducibility of the iron oxide, is found to be responsible for high activity. The catalyst also exhibits high olefin selectivity compared with the others, due to the presence of moderate number of acid sites.