Significant matrix cracks and residual pores may form within ceramic matrix composite which was prepared by polymer infiltration and pyrolysis (PIP) method. Explore the matrix cracking mechanism and the crack evolution behavior would benefit the design and performance optimization of the composite. A spinning PIP process in vacuum was adopted to prepare mini C/SiCN composite without weak interphase. The tensile properties and the matrix crack evolution phenomena were analyzed. The influences of PIP cycles and heat-treatment temperatures were discussed. Results showed that the compositions are essentially the same for the samples heat-treated at 1000-1400 ℃. While the heat-treatment temperature rises to 1600 ℃, the precursor-derived SiCN matrix decomposes, with the carbon content decreased and SiC content increased significantly. As PIP cycles increased from 1 to 4, the average tensile strength of the composite increased by 14.19%, 38.83%, and 63.47%, respectively. The matrix crack spacing and crack opening distance gradually decreased, and the bonding between matrix and fiber was enhanced, leading to little fiber pull-out. When the heat-treatment temperature increased from 1000 ℃ to 1400 ℃, the tensile strength of the composite changed slightly. In contrast, when heat-treatment temperature roses to 1600 ℃, the SiCN matrix was transformed from amorphous SiC_xN_4-x tetrahedron structural units to SiC crystals. Then the matrix and the fiber debonded, resulting in their bonding strength weakened. As a result, the tensile strength of the C/SiCN composite decreased by 30.0%, due to a combined effect of interfacial debonding and fiber damage.