Intravenous thrombolysis is considered as the first choice for ischemic stroke. In the recent years, endovascular therapy is demonstrated to be effective to treat ischemic with big vessel occlusion. However, only a minority of patients can get intravenous thrombolysis or endovascular therapy due to the restricted time window and strict indications. Dual antiplatelet has been demonstrated to be effective in the patients with high risk of TIA or minor ischemic stroke (NIHSS<4). But there is still stroke progression although dual antiplatelet. The ischemic stroke patients with NIHSS > 3 has been recommended to give aspirin in most guidelines. Of those patients, mild to moderate stroke patients (3\

Inclusion Criteria:

1. Age 18-80 years old;
2. Clear diagnosis of ischemic stroke patients with head CT or MRI examination;
3. The time of onset is less than 72 hours;
4. NIHSS score is less than 12 points;
5. the large artery atherosclerosis etiology
6. Signed informed consent.

Exclusion Criteria:

1. Hemorrhagic stroke or mixed stroke;
2. Patients with planned thrombolytic therapy;
3. Serious diseases such as severe infection or liver, kidney, hematopoietic system, endocrine system, etc.;
4. The history of stroke and had serious sequelae (mRS> 1);
5. Allergic to aspirin/clopidogrel and argatroban;
6. ischemic stroke caused by other causes, such as small vessel lesions, cardiogenic embolism, arterial dissection, vasculitis and other cerebral infarction;
7. Previous history of cerebral hemorrhage;
8. It is expected to use other anti-platelet agents or non-steroidal anti-inflammatory agents that affect platelet function;
9. within 3 months of gastrointestinal bleeding or major surgery;
10. any unqualified patients judged by researchers.