Double Randomized and Placebo Controlled Trail of Sanchitongshu Combined Antiplatelet Drug to Prevent Ischemic Stroke

Inclusion Criteria: 1. Age from 20yrs to 85yrs; 2. Anticipated patients within 8-90 days without cardiac ischemic stroke; Responsible lesions of all cases must be confirmed by a head MRI; 3. have ability to take the drugs; 4. No serious complications, liver and kidney function is normal; 5. At least one of the following (a-c): 1. Confirmed by MRA, CTA or DSA that stenosis of intracranial aorta beyond 50% (in A2, M2 or P2) 2. Confirmed by MRA, CTA or DSA that stenosis of cranial artery beyond 50% (carotid artery, intra-carotid artery, vertebral artery, head artery, or lower collarbone artery) 3. ESRS score beyond 3 6. Take Clopidogre or aspirin alone for antiplatelet treatment with informed consent 7. Willing to participate in the clinical trial and willing to be followed up with, have signed informed consent Exclusion Criteria: 1. Younger than 20 yrs or elder than 85 yrs; 2. The neurological function defects caused by brain hemorrhage or other conditions (e.g. vascular malformations, tumors, abscesses or other non-ischemic cerebrovascular diseases); 3. Isolated sensory symptoms (e.g. numbness), isolated visual abnormalities, isolated dizziness and dizziness but have no responsibility lesions in head MRI; 4. Stroke is caused by angiography or surgery operation; 5. Stroke caused by cardio-induced embolism according to TOAST; 6. Anticoagulant evidence (heart thrombosis, such as atrial fibrillation, heart valve replacement surgery operation) 7. Contraindications of MRI examination, such as claustrophobia or implanted pacemakers 8. Severe heart and lung impairment; liver function laboratory indicator AST or ALT is 2x maximum normal value, or renal function laboratory indicator serum creatinine is 1.5X maximum normal value; 9. Plan to accept vascular surgery during the trial period (e.g. epidermal angioplasty, stent placement and bypass transplants, etc.); Surgical or interventional treatment requires discontinuation of research drugs 10. History of drug elution coronary stent implantation within one year 11. Congestive heart failure or uncontrolled Angina pectoris; 12. Platelet reduction (platelet count less than 10000/mm3); 13. Symptomatic non-traumatic intracranial bleeding, any other bleeding disorder, bleeding tendency or clotting dysfunction; 14. History of gastrointestinal ulcers, gastrointestinal bleeding, or surgical history within the last 3 months; 15. Severe complications of non-cardiovascular and life expectancy less than 3 months; 16. Have malignant tumors which in course of treatment; 17. History of allergies to SanqiTongshu; 18. Aspirin users have any of the following conditions: (1) History of allergy to aspirin or salicylic acid analogues (2) Pepsi ulcers (3) asthma or asthma history caused by aspirin; 19. Allergy history of clopidogrel; 20. History of alcohol or drugs abuse in the past 12 months; 21. Pregnant, lactating women, or women who do not take effective contraception; 22. There are other serious diseases or abnormal laboratory results who is not suitable to participate the study; 23. Those who are participating in other clinical trials or clinical trials completed in past 3 months; 24. Patients do not understand the study, or are unable to/unwilling to follow the provisions of the clinical trial.