The effect of pyrolytic carbon (PyC) thickness on the tensile property of mini T800-carbon fiber reinforced SiC matrix composites (mini-C/SiC) was studied in this work. PyC interphase was prepared by CVI process, and the PyC thickness was adjusted from 0 to 400 nm. The results showed that the tensile strength of mini-C/SiC first increased and then decreased with the increase of the PyC thickness. When the thickness of PyC was 100 nm, the average strength reached the maximum value of 393±70 MPa. Weibull modulus increased from 2.0 to 8.06 with the increase of PyC thickness, indicating that the increase of PyC thickness is conducive to reducing the dispersion of mechanical properties.