Abstract: A series of silicon spheres supported cobalt catalysts were prepared by incipient wetness impregnation followed by decomposition under treatment of glow discharge plasma with different intensities. The catalysts were characterized by X-ray powder diffraction, N₂ physical adsorption-desorption, H₂ temperature-programmed reduction, transmission electron microscope and Fourier-Transform Infrared spectroscopy. The Fischer-Tropsch synthesis performance were tested on a fixed bed reactor. The influence of plasma treatment on cobalt dispersion, reducibility and cobalt-support interaction were analyzed and discussed. The results showed that the plasma-treated catalysts had better catalytic performance than the calcined sample. The Co/SP-P650W catalyst showed the highest reaction activity due to the proper cobalt dispersion and higher cobalt reducibility.