The DC resistance of transformer is a must test item in transformer manufacturing, including semi-finished products, finished products factory test, installation, handover test and preventive test of power department. It can effectively find manufacturing defects such as material selection, welding, loose connection parts, missing strand, broken wire and other manufacturing defects and hidden dangers after operation. In order to meet the needs of rapid measurement of transformer DC resistance, our company developed this DC resistance tester by using its own technical advantages. The new power supply technology is adopted in the instrument, which has the characteristics of small volume, light weight and large output current. The whole machine is controlled by single-chip microcomputer, which can automatically complete self-test, data processing, display and other functions, and has the function of automatic discharge and discharge indication. The instrument has the advantages of high precision and easy operation, which can realize the rapid measurement of transformer direct resistance.