Image vectorization plays an important role in the digital image processing. Because the traditional linear vectorization methods have some shortcomings including processing data slowerly, being sensitive to noises and being easy to be distorted, this paper proposes an image vectorization method based on mathematical morphology. This method consists of the image edge detection method based on the four structural elements template, the morphological sequential homotypic skeleton abstraction method based on the eight structural elements template and the vectorization method based on the dynamic change of pace about Freeman's chain code. Examples have proved that this method can abstract high precision skeletons rapidly and attain high accuracy vector data measured by the arc segment. This method has many advantages, such as the faster processing rate, the higher accuracy and the less storage space. So it has certain feasibility and practicability in digital image vectorization.