The SiC coating was deposited by high power plasma spraying (HPPS) on carbon/carbon (C/C) composites. Three sets of parameters were selected to optimize the properities of coating. The anti-ablation property of SiC coating was investigated by oxyacetylene torch flame at 1500℃. The phase composition, microstructure and component of coatings were analyzed by different methods included X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) respectively. The results shows that the porosity of three sets of coating is 21.3%、17.4% and 15.3%. The plasma jet field has a more suitable temperature field and velocity field under the condition that the main gas flow is relatively high and the auxiliary gas flow is low. SiC powders were heated more fully to achieve better melting state and obtain larger kinetic energy. Therefore, the deposition rate of the coating increases gradually and the porosity decreases gradually. SiC powders were oxided to form amorphous SiO2. After been ablated for 300s，the SiC coating provide effective protection for the matrix. Because of the temperature gradient caused by the oxyacetylene on the surface of the sample, the coating forms three kinds of ablation morphology after ablation, including the central dense area, the transition area and the edge of loose area. During the ablation, a dense SiO2 glass layer generated on the surface of central area coating, which is beneficial to block the infiltration of oxygen.