Automatic identification technology of digital display instrument has significant meaning in improving its using efficiency and environment adaptability. As to strokes missing (or character missing) in the image acquisition process, a digital automatic recognition algorithm is put forward. Two-dimensional entropy threshold is introduced in image binarization segmentation to reduce the influence of low or uneven illumination. At the same time, multiple segmentation and coding matching method is used to identify the missing characters and numbers. After a variety of instrument recognition experiments, the results show that this method can meet the time and accuracy requirements in digital display instruments, and has better adaptability to situation like image tilt, zoom and so on.