Sample size is calculated from one relatively well designed study. According to this study, the migraine attack frequency each month after treatment in the verum acupuncture group was 4.8 ± 3.8 times, and in the sham acupuncture group 7.8 ± 3.7 times. Based on a power of 0.8 to detect a significant difference (α = .05, two-sided), 32 participants will be required for each group, which is calculated by R software Version 0.96.122 (RStudio, Boston, MA). Allowing for a 20% withdrawal rate, a total of 120 participants will be enrolled with 40 participants in each group.