Headache is a common phenomenon in daily life and a common clinical symptom. Imaging is the main diagnostic method, commonly cranial CT and cranial MRI, CT and MRI have their own characteristics, generally speaking, CT is better for bony structures and hemorrhagic diseases, MRI is better for soft tissues, has more weighted patterns, and is more expressive for complex structures. The expressiveness is better, and it is important to choose the examination method reasonably for the possible etiology. If the headache is caused by trauma, cranial CT examination is usually required. Cranial CT examination is very important for the diagnosis of traumatic brain injury, and is an important basis for determining the severity of the disease and choosing the treatment. Headache caused by traumatic brain injury is generally not necessary to do cranial MRI. If the headache is considered to be an intracranial occupying lesion, such as brain tumor, a cranial CT examination can be done first, and if a tumor or other condition is found, a cranial MRI examination is usually required. Cranial MRI is better than cranial CT for diagnosis, but the price is higher than CT. Therefore, cranial CT examination is generally used as a screening test, while cranial MRI is more beneficial for diagnosis. In case of cerebrovascular lesions, such as cerebral infarction, cranial MRI is usually done, and if necessary, a bit of MR angiography is done. To sum up, there are more causes of headache, and CT and MRI examinations have their own characteristics, so it is necessary to choose the examination method reasonably for the possible causes.