Abstract: The resin transfer molding (RTM) process was used to prepare the three-dimensional angle interlocking woven layup composites. The influence of the layer thickness on the tensile properties and failure mechanism was emphatically discussed. The results show that the tensile strength increases significantly with the enhancement of the layer thickness. In the case of similar fiber volume content, the layer thickness has little effect on the tensile modulus. In the process of tensile fracture, the break of each layer is not synchronized, and the augment of layer thickness deepens the diversity in failure strain between the individual layers. The failure samples have significant delamination, no obvious cracks appeared in the layer. The warp yarns show obvious brittle fracture and a large amount of resin chips appears in the interlamination. The failure modes mainly include fiber fracture and extraction, interface debonding, matrix cracking and delamination.