There are two arms in our trial, DCB group, BMS group.The investigators are going to investigate the safety and efficacy of all groups at 6 months and 12 months.

Inclusion Criteria:

1. aged between 18 and 80 years old;
2. TIA or non-disabling ischaemic stroke of the posterior circulation;
3. symptoms occurred in the 14 days and could not be relieved after 2 months of regular medication
4. stenosis of the vertebral artery of 50% or greater, diagnosed by both CT angiography or angiography;
5. NIHSS≤ 6;
6. score on the modified Rankin scale ≤ 3.

Exclusion Criteria:

1. Active bleeding or coagulation disorders or severe renal/liver impairment
2. allergy to iodinated contrast agent or related medicines;
3. acute stroke in 3 weeks
4. more than 1 stenosis at the target vessel or Distal vascular dysplasia (diameter≤3mm)
5. a potential cause of stenosis other than atherosclerosis
6. Severe stenosis was found in the anterior circulation artery(>70%)
7. intracranial hemorrhage or hemorrhagic stroke, intracranial tumor, cerebral arteriovenous malformation, or intracranial aneurysm in 30 days;
8. ISR patients;
9. Severe calcification lesion；
10. obvious thrombosis in vessel;
11. pregnancy;
12. a potential cause of TIA or minor stroke other than stenosis in a vertebral artery.

patients meet all of the inclusion criteria and none of the excusion criteria