Abstract: To address the issue that the hole-making process has significant influences on the service performance of composites and their components, hole-milling experiments on carbon/epoxy 2.5D woven composites were conducted. Comparisons on seven indicators, including the entry & exit hole diameter deviations, the hole verticality errors, the hole taper errors, the entry & exit roughness, and the hole wall roughness were established. To improve hole quality, an optimized milling process was presented. A method combining digital image correlation technology and tensile testing was employed to evaluate both the warp tensile strength and the surface strain distribution of the open-hole composites. The results indicate that with the optimized milling process, the tensile strength retention rate of the open-hole samples was increased by 6.29%, reaching 71.43%. Under the strain level of 20%, the stress concentration factor was reduced by 8.13%, while the stress concentration factor before failure was decreased by 1.90%. During the tensile process, the uniformity of the surface strain distribution around the hole was improved significantly. The propagation of cracks along the thickness direction of the samples around the holes are effectively blocked by the 2.5D woven integral architecture, while the open-hole tensile strength of the material is retained to a greater extent. This piece of work has important theoretical guidance for the development and applications of carbon/epoxy 2.5D woven composites.