Abstract: Using N-methylpolyborosilazane (PBSZ) as precursor, SiBNC fiber (SiBNC_f) as reinforcement fiber, SiBNC_f/SiBNC ceramic composites were fabricated by precursor polymer pyrolysis conversion and hot-press sintering method. The evolution of oxidation mechanism and kinetics of oxidation behavior of SiBNC_f/SiBNC composites were investigated by non-isothermal oxidation tests under 800-1 500 ℃ for 1-3 h in air. The morphology and phase of SiBNC_f/SiBNC ceramic composites before and after oxidation resistance were analyzed by means of SEM and XRD. The density, porosity and mechanical properties of composites were tested by Archimedes drainage volume method and three point bending test method. The results show that SiBNC_f/SiBNC ceramic composites possess of outstanding oxidation resistance and high temperature stability. The prepared oxidation film can effectively block the entry of oxygen, and effectively fill the crack in SiBNC_f/SiBNC composites and hole defect. The SiBNC_f/SiBNC composites possess of high temperature self healing performance.The density of SiBNC_f/SiBNC composites can be improved after oxidation, which can enhance the three point bending strength largely. As the density increase from 1.67 g/cm³ to 1.86 g/cm³, porosity decreases by 41%, bending strength inceases from 7.51 MPa to 26.54 MPa.