Titanium aircraft parts joint lug groove machining plagued aerospace manufacturers. Aiming at titanium aircraft parts joint lug groove machining difficulties, the causes of the poor lug groove machining quality were analyzed indepth, various verification process were conducted for the joint lug grooving machining, a conventional offstress machining method was proposed, and a set of milling apparatus was designed for machining the joint part. Then rapid processing to titanium lug groove was achieved. Not only the joint part earsided surface quality is ensured,but also the joint part lugs shut phenomenon is eliminated.