In order to solve the problem of extracting features of flaw images of gun bore, extracting textural features of flaw images is proposed. The characteristics of several kinds of flaws of gun bore are analyzed. The concept of grey level co-occurrence triangular matrix (GLCTM) and four parameters of grey level co-occurrence matrix are applied to extract features of images. The experimental results show that the proposed method can abridge calculation time and reflect grey airspace information of images well, so the proposed method is effective.