Stroke is a highly prevalent and dangerous cerebral blood circulation disorder, also known as cerebrovascular accident, and is divided into ischemic stroke (cerebral infarction) and hemorrhagic stroke (cerebral hemorrhage). Therefore, whether the early diagnosis is correct will directly affect the treatment effect. However, there are limitations in conventional MRI sequences and CT for displaying small hemorrhagic foci in the early stages of cerebral infarction. SusceptibilityWeightedImaging (SWI) is one of them, which can show special low-signal hemorrhagic foci at an early stage, so the main advantage is that it is highly sensitive to hemorrhagic foci. Magnetic susceptibility weighted imaging (SWI), which is essentially BOLD imaging, is a new technique based on T2WI weighted gradient echo sequences to show the difference in magnetic susceptibility between different tissues. The vast majority of substances that cause magnetic susceptibility effects in humans are related to iron, and SWI is highly sensitive to paramagnetic substances such as deoxyhemoglobin and iron-containing hemoglobin. Therefore, its greatest advantage is its high sensitivity to hemorrhage, which can clearly show tiny hemorrhagic foci, and the display rate of hemorrhagic foci can reach 100%. In hyperacute cerebral hemorrhage, due to the rapid de-oxidation of blood at the interface of hematoma and tissue, resulting in local magnetic field inhomogeneity, when the low signal ring around the hematoma is not obvious on T2WI, it can show obvious low signal ring on SWI, which can distinguish cerebral hemorrhage and cerebral infarction at an early stage. Hemorrhagic cerebral infarction is a reperfusion injury hemorrhage that occurs after the occurrence of ischemic infarction due to the regain of blood in the infarcted area, which can be caused after anticoagulation and thrombolytic therapy, and may lead to serious consequences if improper treatment is taken without timely detection. Therefore, the early diagnosis of hemorrhagic cerebral infarction is of great significance to whether thrombolytic and anticoagulant therapy is performed clinically. SWI sequences can detect multiple punctate and nodular low-signal hemorrhagic foci in the cerebral infarct area at an early stage, which can promptly guide the clinic to change the treatment plan. SWI sequence can not only diagnose the type of stroke early, but also be sensitive to underlying diseases such as subarachnoid hemorrhage, diffuse axonal injury (DAI), cavernous hemangioma, developmental venous malformation, tumor, etc. It can also observe hemorrhagic changes after cerebral infarction, which is important for clinical diagnosis and treatment.