Abstract: With the development of oil and gas fields,oil casing deformation,damage and corrosion problems caused by various factors have seriously affected the normal production of oil and gas.Electromagnetic inspection of MID-K and multi-arm caliper logging technology used by North China Engineering Logging Branch in casing damage monitoring can not only estimate oil casing deformation characteristics and confirm the degree of corrosion damage of pipe wall but also check the well limb structure,evaluate the speed of casing damage and predict the casing life.At present,the technology is widely used in many blocks such as Daniudi,Mahuangshan,Hangjinqi and Xinjiang and has been successfully used in more than 70 wells.Engineering problems in production wells like well leakage,column deformation and oil casing deformation,damage,corrosion and crust are effectively solved.Significant effects have been proved in comprehensive treatment of damage parts in such aspects as oil casing,remoulding and improving oil and gas well production capacity,enhancing the service life of oil casing and reducing the workover cost.