Abstract:Measurement of inner diameter of gun barrel belongs to blind measurement technology, which is the necessary technical means for the quality monitoring and maintenance of the gun bore. This thesis analyzed the measure technology defect for inner diameter of various current cannon , a new measure technology based mutual inductance drift sensor for inner diameter are presented, the result of the operation can be displayed in real time through computer control. Measure system are developed for small caliber of rifled gun. It is characterized by high measure precision, portable, easy operation, economic and durable. It can be widely used in the measurement of the inner diameter of various caliber gun barrels. The result have been patented and applied by the national defense invention.