A Sm2O3 decorated carbon aerogel (CA-Sm) was successfully synthesized through a sol-gel from resorcinol, phloroglucinol (P), formaldehyde and catalyst of oxalic acid and doping compound with Sm2O3 strategies. The small amount of active reactant phloroglucinol promotes synthesis of carbon aerogel (CA) and formation of uniform and porous carbon spheres. The CA-Sm composites present an interlinked porous structure and high specific surface area. The CA-Sm with sulfur loading (CA/S-Sm) from the composite via molten sulfur technique exhibits an enhanced performance with long-term cycling stability and high rate capacity. In particular, the cathode of CA/S-Sm-2 with Sm/C molar ratio of 2/400 achieved a high initial discharge capacity of 1347 and 976mAhg−1 at 0.2C and 2C, respectively. And the cathode exhibited a nice long-term cycling stability with a high initial discharge capacity of 1175mAhg−1 and maintained 861mAhg−1 after 300 cycles at 0.5C. The excellent electrochemical performance of the battery is attributed to interrelated nanospheres, porous carbon structure, large specific surface area of Sm2O3-doped CA composites and improved electronic and ionic transport at the cathode.