The paste attenuation mentioned in this paper is a conductive coating flaw on flexible printed circuit board. For avoiding harmful effect caused by paste attenuation on FPC trace, which would cause economical losses, it is a reasonable way to locate the position of paste attenuation for the later repair or get rid of the unqualified board directly. However, the size of paste attenuation flaw is uncertain. And the non-uniform illumination results in the non-uniform of image grayscale. Also trace region crisscrosses with the background. The above reasons increase the difficulty of trace paste attenuation detection. Aiming at this problem, a detection scheme is proposed which made up of adaptive directional template and gray difference, based on the detailed analysis of paste attenuation texture and trace morphological feature. First of all, the trace region after preprocessing is traversed with ADT template according to skeleton tracking process, then the large paste attenuation regions, diminutive paste attenuation regions and the whole candidate pixels relative to the ADT template size, thus, the preprocessed image is segmented into several diminutive regions. Secondly, the noise regions which are not flaws are eliminated utilizing the numerical relationship of diminutive regions energy tendency value and default threshold. At last, the non-deficit regions gained after the above two steps processing are screened again via method of gray difference, then the middle region of large paste attenuation texture is extracted, thus, the whole paste attenuation texture detection is completed. Results show that the paste attenuation flaw detection EER of suggested method is 3. 93 percent on the testing of self-built image storage SUT-F2, which decreases at least 5. 28 percent compared to the other typical methods of textural features extraction and paste attenuation flaw detection. The above facts prove the high efficiency and actual value of suggested method.