In aerospace engineering, it is important to study the influence of wet and thermal environment on the interlayer fracture toughness of resin matrix composites. In this paper, the microstructure of type I and type II interlayer fracture toughness experiments under different wet and thermal conditions were analyzed, and the effect of wet and thermal environment on the interlayer fracture toughness of resin matrix composites was obtained. The research results indicate that the humid and hot environment has a completely opposite effect on the interlayer fracture toughness of type I and type II resin composite materials. As the temperature increases, the interlayer fracture toughness of type I resin composite laminates shows an upward trend, while the interlayer fracture toughness of type II resin composite laminates shows a downward trend. During Type I delamination, a large number of fiber bridging phenomena occur. In humid and hot environments, the resin softens and fiber bridging phenomena increase, leading to an increase in Type I interlayer fracture toughness with increasing temperature; In a humid and hot environment, as the temperature increases, the shear strength of the resin gradually decreases, and the interfacial shear strength between the resin and fibers also gradually decreases, resulting in a decrease in type II interlayer fracture toughness with increasing temperature.