Background: Tai Chi is a body-mind exercise. It’s prophylactic efficacy on migraine attack remains largely unknown. The purpose of this study was to examine the effect of a 12-week Tai Chi training on the migraine attack days per month, body composition, and blood pressure (BP) in a sample of Chinese women with episodic migraine. Method: A two-arm randomized controlled trial was designed. Eighty-two local women aged 18 to 65 years and diagnosed with episodic migraine were randomized to the Tai Chi group or the waiting list control group. A modified 32-short form Yang-style Tai Chi training with 1 hour per day, 5 days per week for 12 weeks was adopted as intervention. An additional 12 weeks follow was conducted. The control group received a “delayed” Tai Chi training at the end of the trial. The difference in migraine days between 1 month before baseline, 3rd month (12nd week) and 6th month (24th week) after the randomization were examined. The changes in weight, body fat, and BP before and after the intervention were also analyzed. Results: Of 189 women screened, 82 eligible women completed the baseline assessment. After randomization, 9 women withdrew immediately, finally 40 in Tai Chi group and 33 in control group were involved in the analysis. On average, women in Tai Chi group had 3.6 (95% CI: -4.7 to -2.5, P<0.01) days reduction of migraine attack. Compared with control group, the difference was statistically significant (P<0.001). Tai Chi group also lost 0.6 kg of body weight and 0.6% of body fat at the 3rd month, and 10.8 mmHg systolic BP at the 6th month, respectively (all p<0.001). The between-group difference of systolic BP was -6.9 mmHg (95% CI: -11.6 mmHg to -2.1mmHg, p<0.05), whereas no significant differences were observed regarding weight and body fat at the 3rd month (all p>0.05). Among Tai Chi group, change in systolic BP was significantly correlated to the change in migraine days (P<0.05). Conclusion: The 12-week Tai Chi training significantly decreased the frequency of migraine attack and improved the systolic BP. The association between migraine attack reduction and BP improvement needs further investigations.