The invention belongs to the technical field of medical image processing, and discloses a blood vessel image segmentation method based on centerline extraction, a nuclear magnetic resonance imaging system, and preprocessing of brain blood vessel data by vesselness filtering based on Hessian matrix; topology refinement method for blood vessel centerline Extraction; take the centerline point as a positive sample and the non-vascular point as a negative sample to extract the features of the training sample and the test sample; use the features of the training sample and the corresponding label to train the SVM model, and use the feature of the test sample as the input of the trained SVM model , the output label is the segmentation result of blood vessels. The invention reduces the workload and improves the calculation efficiency; it does not need to manually calibrate the target and the background, completes automatic blood vessel segmentation, and greatly improves the segmentation efficiency. The invention realizes the segmentation of cerebral blood vessels, which is accurate, fast and does not require human intervention; the true positive rate and true negative rate can reach 0.85.