Abstract: In water injectors, service conditions are complicated, and string corrosion, fatigue failure and seal failure happen from time to time, which brings great challenges to well integrity management. Current well integrity standard cannot distinguish producers and water injectors strictly, and the well barrier classification method of water injector has many defects. Referring to NORSOK D-010 standard, combining with the status of water flooding development, this paper analyzed the working state particularities of the well in a water injector, discussed the reasons for the failure of well barrier and determined key well barrier components. The well barrier system of water injector was established, in which the downhole safety valve is removed out of the primary well barrier and the tubing pipeline and components between well and downhole safety valve and the No.2 main valve of christmas tree are included in the category of primary well barrier. The acceptance standard of key components were discussed, and the design contents of the well integrity of water injector were discussed from five aspects, i.e., well barrier setting, corrosion control, service life prediction, operation parameter control and well data record. In this way, the design process on the well integrity of water injector was finally developed, which is of great significance to guiding the safe, stable, efficient and cost-effective water flooding development of each oilfield.