Abstract: The near-stoichiometric ratio SiC fiber and polycarbosilane were used as fiber reinforced phase and matrix precursor to prepare SiC/SiC composites by polymer precursor impregnation cracking process through polymer precursor infiltration and pyrolysis (PIP) method. The morphology of SiC fiber and SiC/SiC composite was analyzed by SEM technology, and the mechanical properties of the material were tested by three-point bending method. Result showed that the near-stoichiometric ratio SiC fiber had the characteristics of high strength and high modulus,?and the pyrolytic carbon interfacial layer occupied important influence on mechanical properties and fracture behavior of SiC/SiC composites. The mechanical properties of SiC/SiC composites first increased and then decreased with the increase of the thickness of the pyrolytic carbon interfacial layer. For the polymer precursor infiltration and pyrolysis method based on the intrinsic characteristics of the near-stoichiometric ratio SiC fiber, the suitable interface layer thickness of the SiC/SiC composite is 0.10μm-0.15μm.