Based on experimental analysis of 2.5D-C/SiC composite, mechanical behavior and damage evolution process under tensile loading were investigated. Tensile damage evolution models in terms of stress and strain for 2.5D-C/SiC composite were presented to disclosure tensile damage evolution law. Experiment shows that the tensile damage process of 2.5D-C/SiC composite along longitudinal and transverse direction is similar, and that tensile stress-strain curve is nonlinear and approximately consists of 3 fold lines corresponding to three specific tangential moduli. The damage process includes three stages: the first is initial damage stage in which the initial micro-cracks of composite cracking; the second is accelerating stage that new micro-cracks appears and opens; the last is decelerating stage that the deflection of micro-cracks and debonding of fiber/matrix interface are major damage mechanisms.