Abstract: In order to validate the relationship between structure and mechanical properties of 2.5-D woven fabric composites, the unit cell geometry model of 2.5-D woven composites was built by adopting the assumption of raceway fibers on the basis of the micrograph observation and ananlysis of the fabric section. The geometry model formular is used to deduce the length of yarns, the orientation angle of the nodulated yarns and the fiber volume content on some typical 2.5-D woven composites, such as shallow curve-linking structures, shallow straight-linking ones, and deep angle-linking ones, and tensile strength and compress strength of the composites are forecated. Experimental samples of meeting the need of 2.5-D woven composites are made and experiments are performed. Theoretical predictions agree well with the experimental results, thus the proposed model is verified.