The risk period of cerebral infarction is closely related to the period of cerebral edema. Generally speaking, cerebral edema begins to appear at 24 hours, and gradually reaches its peak in 7-10 days, after which the cerebral edema slowly subsides. Cerebral infarction is due to the cerebral artery blood flow is reduced or interrupted, so that the artery blood-supplying area occurs in the acute brain cells ischemia, hypoxia, brain cells hypoxia, so that the intracellular osmotic pressure increases, and then the formation of intracellular edema. Usually, cerebral edema appears about 1 day after the onset of the disease, and it takes about 2-3 weeks for it to subside completely. In case of large cerebral infarction, the scope of cerebral edema is larger, and even the edema period can be more than 1 month. In addition, besides cerebral edema, factors affecting the risk period of cerebral infarction also include the location of infarction, the presence of complications, age, and the presence of chronic diseases, etc., which should be analyzed on a case-by-case basis. In conclusion, the risk period after cerebral infarction is different for different patients, and it is recommended to make a comprehensive judgment according to the specific condition of the patient. Timely and active cooperation with the doctor’s treatment can help patients get through the dangerous period.