To improve the low accuracy of breast X-ray medical image multi-class classification， a new medical image multi-class classification method based on edge detection is proposed. The breast X-ray medical image is firstly preprocessed, including image denoising and enhancement. Tumor region in X-ray medical image can be acquired through edge detection algorithm. Feature selection on tumor is implemented using gray level co-occurrence matrix. This method uses support vector machine (SVM) to classify the medical image according to selected features. The X-ray medical image without any detected edge can be directly classified into the normal without breast cancer. The experiment result shows that the new medical image multi-class classification method based on edge detection has a higher precision than the traditional SVM multi-class classification algoritm on breast X-ray medical image. 