A certain number of stitching holes are randomly distributed in SiCf/SiC composites prepared by CVI method. The existence of these stitching holes disrupts the continuity of the internal fiber bundles and has a certain influence on the mechanical properties of the materials. In order to study the influence of stitching holes on the tensile behavior of plain-woven SiCf/SiC, this paper uses CT technology to scan the interior of plain-woven SiCf/SiC to obtain the morphology and distribution of the internal stitching holes. Then, cells containing stitching holes were modeled to study the influence of different characteristics of stitching holes on the tensile behavior of SiCf/SiC. Finally, the tensile behavior and damage process of the cell with stitching hole at the fracture location of the specimen and the cell with stitching hole near the fracture location were studied by modeling the specimen level cell with the thickness of the specimen. The conclusions are as follows: (1) A certain number of stitching holes were randomly distributed inside the specimen. The inclination angles of the stitching holes are mostly 70°–80°, and the radius of the stitching holes is mostly 0.25 mm–0.28 mm (2) The influence of stitching hole characteristics on the tensile behavior of plain-woven SiCf/SiC is as follows: Position > Hole radius > Inclination angle. Among the positional characteristics, the Type-Ⅱ model has the greatest influence on the weakening of the tensile behavior due to more pronounced stress concentration phenomenon. (3) The stitching hole at the edge of the specimen has the greatest influence on the weakening of the specimen strength and is accompanied by obvious stress concentration. In the section containing the stitching holes, the maximum local stresses in the fiber bundle and matrix are about 1.5 times that of the other two models, resulting in earlier damage initiation and faster accumulation.