In order to reevaluate safety and efficacy of human urinary kallikrein in treating acute cerebral infarction ,a multi-center, open label , single group study was designed. Expect to enroll 60 sites and 2186 subjects. Subjects will receive kallikrein treatment according to real clinical practice (suggest above 14days treatment) and 90 days follow up

Inclusion Criteria:

1. Acute anterior circulation cerebral infarction diagnosed ≤ 48h;
2. First time diagnosed or have history of acute anterior circulation cerebral infarction without serious sequelae(mRS=0-2);
3. Age from 18 to 80 years old;
4. National Institute of Health stroke scale(NIHSS) from 6 to 25;
5. Have provided signed written informed consent from the patient or the patient's legal representative.

Exclusion Criteria:

1. Brain CT shows cerebral hemorrhage disease: cerebral hemorrhage, subarachnoid hemorrhage, etc.
2. Transient ischemic attack(TIA);
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. Cases treated with thrombolysis / stent surgery or expected to be treated with thrombolysis / interventional therapy / stent surgery.
6. subjects with bleeding disorders at Past or present, laboratory tests: INR > 1.5 or APTT > 2 times;
7. subjects with abnormal liver function (ALT/AST > 1.5 * ULN) and abnormal renal function (Cr> normal upper limit);
8. subjects with history of epilepsy or other serious systemic disease before onset of AIS refused by PI to enroll ;
9. subjects with cardiogenic stroke or cardiogenic stroke related high-risk factors identified by PI, such as atrial fibrillation, echocardiography or Mural thrombus etc;
10. subjects diagnosised any malignancy (except basal cell carcinoma) within 5 years prior to the start of the study;
11. subjects with severe dementia or can't cooperate to evaluate identified by PI;
12. suffering from severe hypertension and failed to control :systolic blood pressure ≥200mmHg (26.6kPa) or diastolic blood pressure ≥110mmHg (14.6kPa); hypotension: systolic blood pressure< 90mmHg and/or diastolic blood pressure< 60mmHg
13. subjects be allergic or intolerant to kallikrein at past;
14. subjects be pregnant/lactating or possibly and planned pregnant;
15. subjects be unsuitable for this clinical study identified by PI.