In this paper, a novel approach combining image enhancement and improved Canny-based edge detection for the thermal wave radar imaging (TWRI) was proposed to identify the internal delamination defect in carbon fiber reinforced polymer (CFRP) components. Experimental testing on artificial CFRP delamination defects was carried out. The fused method is used for defect identification. An image enhancement algorithm was firstly used to improve the contrast of the detection image. An adaptive Gaussian filter was subsequently selected to smooth the detection image for suppressing the effect of noise, and a Sobel operator with eight-directional convolution template was utilized instead of the Canny operator to calculate the gradients. A double-threshold concatenation was lastly employed to establish the contour of the defect areas. The traditional image edge detection methods and the combined method were compared and investigated. The experimental results showed that the internal delamination defects can be recognized with better sharpness and edge details by the proposed method based on image enhancement and improved Canny edge detection.