To improve the ablative properties of ZrC-SiC ceramics, a series of ZrC-SiC multiphase ceramics modified with different contents of La₂O₃ and LaB₆ were prepared by discharge plasma sintering method at 1600 ℃ and 50 MPa. The ablative properties of the materials were tested under oxygen-acetylene flame with a heat flux of 2380 kW/m². The results show that the addition of La₂O₃ and LaB₆ not only improves the sintering performance and density of ZrC-SiC, but also improves the thermal shock resistance. With the increase in addition amount, the surface oxide layer of the samples gradually becomes intact from fracture after ablation. In contrast, the ZrO₂-La₂Zr₂O₇ solid solution layer formed on the ablative surface after La₂O₃ modification still has more holes and cracks, and the combination with internal ceramics is poor, resulting in the poor protection effect. With the addition of LaB₆, the volatilization of low melting-point borides during ablative process can reduce the ablative temperature of the material by nearly 300 ℃. La₂Zr₂O₇-LaBO₃-ZrO₂ outer oxide layer with good thermal stability and lanthanum-rich Zr-O-La-B inner oxide layer with good adhesion are formed on the surface of the ablation center of the sample. The double-layer protective film becomes a dense barrier to prevent the oxidation air from entering the inside of the material, which effectively improves the ablation resistance of the material. The ZrC-SiC ceramic with 20vol% LaB₆ has the best comprehensive ablative performance. After oxygen-acetylene ablation for 60 s, its mass and linear ablative rate are 7.5×10^-4 g/s and 2.1×10^-3 mm/s, respectively.