The utility model relates to a semi -girder style electric drill, it includes the stand, and the bottom of stand is equipped with the supporting seat, and it has the pendulum rocking arm to articulate on the stand, and one side of stand is connected with the spout that vertical setting just can reciprocate through the connecting rod, and the middle part of pendulum rocking arm articulates on the stand, and one of them end hinge of pendulum rocking arm connects installs the handle at bottom, the other end of spout, vertical slidable mounting has by hand wheel actuating mechanism driven telescopic jib (boom) on the spout, and the top of telescopic jib (boom) is connected with the extension rod, the top portion installation electric drill of extension rod, and the power switch of electric drill is on hand. The utility model discloses can avoid the operating risk of ascending a height, convenient operation uses manpower sparingly and can increase work efficiency.