A simplified method was put forward on a binary image contour line extraction. Distance between centroid and dots on contour line was calculated, and based on the maximum centroid dot distance, a feature victor including twelve direction segments and lengths of contour line was studied in this paper, and two distance algorithms based on euclid distance were promoted. The experimental results show that the correct recognition ratios on three kinds of paddy seed reach respectively 79.89%, 89.63% and 93.27%. This method can also be applied to fuzzy pattern recognition on fruits, machine parts etc.. As random of object's lay direction and side were taken into account in this paper, and objects are recognized at the same direction and on the same side, so this method can also be promoted to the optic measurements on object rotation angle and any preindicated geometrical parameters.