To detect the delamination, disbond，inclusion defects of the glass fiber composite materials applied in the solid rocket motor, active infrared thermographic non-destructive testing(NDT) is researched. The samples including known defects are heated by pulsed high energy flash lamp. The surface temperature of the samples is monitored by infrared thermography camera. The results of the experiments show that the active infrared thermography technique is a fast and effective inspection method for detecting the defects of delamination, disbond，inclusion of the composites. The samples are also detected by underwater ultrasonic c-scans. The paper concludes that the active infrared thermography NDT is more suitable to rapidly detect the defect in large-area and the underwater ultrasonic c-scans is more suitable to quantitatively identify the defect in local-area.