Blood pressure is not high but headache may be caused by migraine, shoulder and neck syndrome, insufficient cerebral blood supply and other diseases. 1. Migraine: it may be caused by diet, endocrine, environmental and mental factors, etc. It is a recurring, one-sided or bilateral throbbing severe headache, and mostly occurs on the side of the head. 2. Shoulder-neck syndrome: the cervical nerve in the deformed spinal canal, especially the hinge level of intervertebral activity is susceptible to mechanical stimulation and compression by the protruding intervertebral discs and ligamentum flavum resulting in pain, which will radiate to the head, resulting in headache, but generally normal blood pressure. 3. Insufficient blood supply to the brain: some heart disease can lead to weakened heart pumping ability, reduced cardiac output, resulting in insufficient blood flow to the brain, causing insufficient blood supply to the brain, which can lead to headaches. Blood pressure is not high but headache may also be seen in intracranial space-occupying lesions, trigeminal neuralgia and other diseases, if the blood pressure is not high but the symptoms of headache, persistent and unrelieved, the need for timely medical treatment.