The Metabolism Research of KLK Treating Acute Cerebral Ischemic Stroke: Focus on Drug Frequency-Efficacy Relationship

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.