Abstract: Casing corrosion of oil and water wells is a common problem in oilfield development.Casing corrosion of Changqing oilfield is more complex than that of other oilfields at home and abroad.Therefore, we have made research on this difficult problem since 1979. So far, 4 sets of technology including 7 prevent and control techniques of casing corrosion have been taken shape,the casing corrosion problems at various complicated conditions are solved properly. Those techniques lay a foundation for the development of Changqing oilfield. This paper gives a minute introduction to those techniques.