According to the traditional point of view,CT and lumabar puncture are the main means in the diagnosis of subarachnoid hemorrhage(SAH).The values of conventional MRI T1-weighted imaging(T1WI)and T2 weighted imaging(T2WI)are very little in the diagnosis of SAH.With the development of MRI technique and the research and application of novel MRI sequences,the value of MRI are gradually recognized and affirmed in the diagnosis of SAH.and has shown its superiority.MRI isn't inferior to CT in the diagnosis of acute SAH.evidently superior to CT in the diagnosis of subacute,chronic and atypical SAHs and superior to CT in the diagnosis of the complications of SAH.MRI is valuable in screening for intraeranial aneurysms and postoperative follow-up.