The effect of B₄C addition (0, 3 wt%, 6 wt%, 9 wt%) on the mechanical properties and oxidation resistance of Al₂O₃-C refractory ceramics was studies in the paper. The results indicated that the addition of B₄C could reduce the apparent porosity, increase the mechanical strengths and improve the oxidation resistance. After fired at 1100 °C, the specimen with 6 wt% B₄C achieved lowest porosity and permanent linear change. The cold crushing strength was improved from 14.65 MPa to 47.18 MPa. The cold modulus of rupture was significantly improved from 12.1 MPa to 36.29 MPa. When the fired temperature rose to 1450 °C, the lowest porosity and permanent linear change were obtained when B4C additive was 3 wt%. CCS was significantly improved from 12.40 MPa to 57.32 MPa. CMOR was also increased from 7.16 MPa to 28.71 MPa correspondingly. Meanwhile, the oxidation index could be also reduced from 47.6% to 3.9% when B4C content was 6 wt%. These improved properties were due to the formation of liquid phase B₂O₃ by the reaction between B₄C and O₂/CO. The compact structure was constructed by volumetric expansion of B₂O₃.