Abstract: To investigate the thermal shock resistance of 3D C/SiC composites with a thin interlayer under stresses and oxidizing atmospheres whose thickness of the interlayer is thinner than the standard one (200 nm), the thermal shock tests were carried out in the temperature range between 700 and 1200℃ in oxidizing atmospheres under fatigue or creep stresses. Effects of stress and atmosphere on the degradation behaviors of the 3D C/SiC composite were investigated by the residual tensile strength , the stress-displacement curves, the length change curves and the morphologies. It is found that the oxidation of carbon and the degradation saturation of the composite under thermal shock are accelerated by the stress because of the cracks widen. The effect of creep stress on the degradation of the composite is greater than that of the fatigue stress. The residual tensile strength of the composite is enhanced by alimited oxidation and debonding of the interlayer resulted from the oxidizing atmosphere and the stress. It is shown that the thermal shock resistance of the composite with a thin interlayer is good even under the stress