Abstract: The low-carbon magnesia–carbon (MgO-C) composites containing 3% (mass fraction, the same below) carbon were prepared by adding various types of carbon black (CB). The mechanical properties, oxidation resistance at 1100℃ in oxidizing atmosphere, and thermal shock resistance after 5 times dipping in 1600 ℃ molten-steel of the low-carbon composite samples were investigated, compared with a commercial high-carbon MgO-C composite containing 16% carbon. The results show that the mechanical properties, oxidation resistance and thermal shock resistance of the low-carbon samples improve with the decrease of CB particle size. Thermal shock resistance of the low-carbon sample containing nanometer CB N220 is obviously better than other low -carbon samples, and reaches the level of the high-carbon samples.