As the name implies, periodic migraine is mostly periodic, while cluster headache is a continuous attack of headache within a period of time, which is called cluster headache because it can also be continuous. (1) Symptoms: Periodic migraine is divided into migraine with aura and migraine without aura, some of which can be seen as aura symptoms and positive streak aversion test, but not cluster headache. (2) Attack cycle: The attack cycle of periodic migraine is 2 to 20 weeks, with 1 to 12 attacks per year, and 1 to 7 attacks per week during the headache cycle; cluster headache is manifested as multiple attacks per day. (3) Attack duration: Periodic migraine is more likely to have continuous headache attacks, lasting about 25 hours on average; cluster headache is less likely to last more than 2 hours per attack. (4) Pain location: Periodic migraine mostly has bilateral headache or headache not fixed on one side, and the pain is mostly limited to the frontal and temporal side; cluster headache is fixed on one side and radiates to the ipsilateral temporal side and forehead and jaw. (5) Concomitant symptoms: unilateral bulbar conjunctival congestion is seen in cluster headache; periodic migraine is rare. (6) Others: Cluster headache usually starts in middle age, and is more common in men, and the headache often attacks during sleep at night; periodic migraine is more common in women, and the time of onset is variable. The above differentiation points are only relative, and it is necessary to examine the patient comprehensively in clinical practice, so that the diagnosis cannot be made on one or two characteristics, so as not to miss the disease.