The invention relates to on-line detection method and device for surface embossing glass blemishes. An array CCD (Charge Coupled Device) line scan camera is arranged above a glass plate and is horizontally arranged along the width direction of the glass plate; the glass plate longitudinally moves under the action of a driving roller way positioned on a rack; two rows of LED one-line lateral lightilluminating light sources are respectively arranged at both sides of a scan line of the array CCD line scan camera below the glass plate; the two uniform strip-shaped lateral light illuminating light sources separate for a certain distance to form a slit, and structured light illumination is formed in the slit area; after scanned by the array CCD line scan camera, glass blemishes form grayscale images with certain structures, but not just light spots or dark spots, and bubbles and white concretions are distinguished by a computer according to the different characteristics of the structural grayscale images. The invention not only can detect bright blemishes, i.e. opacities, black blemishes, the bubbles, and the like, but also can detect the white concretions and distinguish from the bubbles, and has the advantages of high light intensity and signal-to-noise radio, large signals, accurate detection, good precision, continuous operation and high efficiency.