Evaluate the effectiveness of the of kallikrein in the different drug frequency for acute anterior circulation cerebral infarction.

Inclusion Criteria:

1. Age 18 to 80 years old;
2. First time diagnosed or have history of acute anterior circulation cerebral infarction without serious sequelae (mRS = 0-2);
3. Acute anterior circulation cerebral infarction with large artery atherosclerotic etiology;
4. Ability to randomize within 48 h of time last known free of new ischemic symptoms.
5. National Institute of Health stroke scale(NIHSS) ranges from 7 to 22;
6. signed written informed consent.

Exclusion Criteria:

1. Cerebral CT shows cerebral hemorrhage disease: cerebral hemorrhage, subarachnoid hemorrhage, etc.;
2. Transient ischemic attack;
3. Serious disturbance of consciousness: Glasgow Coma ScaleGCS（GCS）≤8;
4. Combined angiotensin-converting enzyme inhibitor(ACEI) less than 5 half-time (according to its instruction), or need to be treated with ACEI;
5. Past or present suffering from hemorrhagic tendency of the disease;
6. The investigator in consideration of the other condition that the patients doesn't fit to participate in this clinical study.

After the completion of clinical trials ，Through the article published and upload data 。