Abstract: In surface defect inspection, a novel approach was introduced for identifying small defects on the object with non-uniform illumination or homogeneous texture. Firstly, it was to calculate the grey-level standard deviations of each row and each column in the surface image. Secondly, based on the relative variance of standard deviation, it could be confirmed whether defects were occurring or not, and the coordinate of the defect might be fixed on too. Experimental results indicated that the small defect in surface image of product could be identified accurately by this method.