Background: Functional disturbance caused by cerebellar infarction are diversified according to lesion site and size, mutilation characteristics are different. it is difficult to diagnose because its manifestation is complicated. It can show symptoms like vestibule disease, Compartmental syndrome or be masked by brain stem or occipital lobe infarction. In recent years, Diagnosis rate of this disease increase as utilization of CT and MRI. But CT is influenced by bone structure of posterior cranial fossa, so it cant exam small infarction focus. MRI is better.