here are two processing methods of modern deep hole drilling machine, outside chip removing(gun drilling) and internal chip removing(BTA drilling). The oil supply channels and chip removing channels of them were opposite, and the borehole diameter range of them was different. Three structural types of complex deep holes drilling machines as the double spindle double oriented, single spindle double oriented and single spindle single oriented were researched.Larger diameter range of deep holes of complicated machinery parts can be machined, by using both methods of BTA drilling and gun drilling.