Abstract: The inspection of the open tank for large crude oil tanks requires a lot of manpower, material and financial resources, and it also covers a long period. The inspection hence brings a lot of safety and environmental problems. Therefore, on-line inspection technology is applied more and more widely in large oil tank inspection. Potential failure modes of storage tanks include corrosion, rupture and instability, and targeted on-line detection methods are developed for different failure modes. The test data can provide scientific data support for the RBI of the tank as a whole, and provide corresponding strategies for the later management and maintenance of the tank.