Relying on the geotechnical engineering investigation project for a new assembly line of Bohai Shipbuilding Heavy Industry Co., Ltd., by the application of KG940A high air pressure and crawler DTH drill and the use of pneumatic DTH drilling with casing combined with air positive circulation slag discharging, a set of new methods of dry-boring is explored according to complex broken overburden layer, which makes significant improvement in drilling efficiency and drilling quality.