I am not a physician, so I cannot really answer your question, but you may be able to get some information from the following web site (or other sites that address migraines and acupuncture treatments):http://www.acupuncture-treatment.com/he ... raine.html
If your migraines are caused by stress/fatigue rather than a lack of sleep or oversleeping, skipping meals, hormonal changes, contraceptive pills, food allergies, hypersensitivity to nitrites/nitrates or MSG, barometric pressure changes (weather, altitudes), etc., then perhaps Taijiquan may help since some studies have shown that it helps relieve stress. Taijiquan is also thought to regulate the meridian channels found in traditional Chinese medicine. I think that if you have tried acupuncture and found it to be effective, then Taijiquan may be an effective preventative strategy that may reduce (or eventually eliminate) acupuncture treatments. If you have not obtained relief through acupuncture treatments, then I would suspect that Taijiquan may not help your specific type of migraines.
Note that “...prevention by avoiding accumulating stress...” is emphasized in the following quote from the above web site. For this, a regular practice of Taijiquan may be helpful, and I doubt that it would cause any harm (but may require long term practice as immediate results, to me, seem unlikely).
Compared to tension-type headaches, treatment during migraine attacks requires extra care and consideration. The relaxation response typically induced by the therapy may trigger or intensify the migraine for the reasons previously discussed. For migraine treatment, it is rather important to shift our focus to prevention by avoiding accumulating stress and minimizing the continuous hyperexcitation of the sympathetic nervous system in order to prevent eliciting the exaggerated parasympathetic rebound response. Theoretically, if the predevelopment stage of the migraine involving excessive vasoconstriction can be prevented, the entire headache episode can be avoided all together.
You may also want to check the following thread (or search the forum for other posts concerning stress):viewtopic.php?f=8&t=745