The well-dispersed CoSb3 nanoparticles within mesoporous carbon had been fabricated by wet-impregnation followed by reduction route. X-ray diffractometer (XRD) and transmission electron microscope (TEM) were used to analyze the synthetic process. These CoSb3 nanoparticles had spherical morphologies with sizes around 20 nm. The use of mesoporous carbon effectively avoided the aggregation of these CoSb3 nanoparticles and kept them dispersed well. The results showed the proper ratio of Sb/Co (= 5), a short reaction duration and high temperature played key roles on obtaining pure CoSb3.