Cerebral infarction (CI) is a kind of ischemic stroke (ischemicstroke), accounting for about 70% of all strokes, is a common disease of the brain caused by blood supply disorders of brain tissue. The main cause of ischemic stroke is the reduction or disappearance of blood flow in the blood supply area of cerebrovascular due to thrombosis, embolism of dislodged embolus, and cerebrovascular lesions in the neck and intracranial blood vessels, resulting in ischemia and hypoxia of brain tissues in the blood supply area of the blood vessels and damage and necrosis of brain tissues. Its clinical manifestations mainly include hemiparesis, aphasia, sensory deficits and other neurological deficits. For patients with onset <6h, thrombolytic therapy and interventional thrombolytic therapy can be performed in a timely manner, while thrombolytic therapy is not recommended for patients with onset time >6h. Early diagnosis and treatment can avoid or reduce the damage of brain tissue and achieve better therapeutic effect; if not diagnosed and treated in time, it will eventually lead to irreversible necrosis and softening of brain tissue, and more serious sequelae such as paralysis of limbs, etc. Therefore, the early diagnosis and treatment of cerebral infarction can directly affect the healing effect of the patients, and the key to early diagnosis is to choose the appropriate examination methods. Cranial CT scanning and cranial MRI imaging are the commonly used examination methods for diagnosing cerebral infarction, and cranial CT is more sensitive to the display of intracranial acute cerebral hemorrhage lesions, while MRI has an obvious advantage for hyperacute and acute cerebral infarction. Within 12～24h of cerebral infarction, the density of brain tissue does not change in cranial CT, it is difficult to make accurate diagnosis, and it is often necessary to show the low-density cerebral infarction foci with unclear boundaries after 24～48h, and it is also necessary to find the foci with the more advanced multilayer spiral CT for about 24h, and it is also necessary to find the foci with fuzzy effect due to the similarity of density of infarcted tissues with normal tissues in subacute phase of cerebral infarction. In the subacute stage of cerebral infarction, the density of infarcted tissue is similar to that of normal tissue, resulting in a blurring effect that cannot be distinguished, which can easily lead to the underdiagnosis of cerebral infarction. Within 6h after cerebral infarction, due to cytotoxic edema, the water content of infarcted area is increased by 2%~3%, causing T1 and T2 prolongation, at this time, MRI can find the lesion, which is manifested as a cerebral infarction lesion with low signal of T1WI and high signal of T2WI; after a few minutes of cerebral infarction, the energy metabolism of the brain tissues is damaged, the Na-K/ATPase and other ionic pumps fail, and a large amount of extracellular water enters into the cells, causing intracellular water molecules to be destroyed, which can cause a large amount of intracellular water. The increase of intracellular water molecules and the decrease of extracellular water molecules caused by the restriction of diffusion of water molecules can be found on DWI sequence as early as after 30 minutes, and high signal cerebral infarction foci (restriction of diffusion) can be found, and the ADC value is reduced, and the abnormal signals can be sustained for 3~5 days, which shows that the DWI has a high sensitivity and specificity for the display of cerebral infarction foci in the super-acute stage, and it can discover the super-acute stage, It can detect hyperacute and acute cerebral infarction, which can greatly shorten the diagnosis time of cerebral infarction and provide therapeutic basis for early thrombolytic therapy, and at the same time, cranial cerebral angiography (MRA) can also clarify the obstruction, stenosis site and degree of the diseased blood vessel that causes cerebral infarction. In summary, MRI has good soft tissue resolution, can clearly show the cerebral infarction foci, and is significantly better than CT in the diagnosis of cerebral infarction in the hyper-acute and acute phases, and at the same time, cranial cerebral angiography (MRA) is also able to clearly define the cerebral infarction diseased blood vessel condition, so for the clinical suspicion of acute cerebral infarction (including those who have already done CT examination and did not find any abnormality), hemorrhagic cerebral infarction, and cerebral infarction patients suspected to have new infarction, routine cranial cerebral MRI should be timely performed. Routine cranial MRI imaging should be performed in a timely manner, and DWI sequences should be taken as mandatory sequences, so that hyperacute and acute cerebral infarction can be detected at an early stage, and leakage and misdiagnosis can be avoided.