Based on dynamic analysis and reservoir simulation, remaining oil distribution in HN oilfield was studied.A new injector location was designed considering structure and sand distribution maps.According to the watercut distribution, the M1 reservoir was divided into two areas, low watercut stage area, and high watercut stage area.Different strategies were made for these two areas, gentle water injection for low watercut area, and strong water injection for high watercut area.And finally, water injection rates were designed for the two injectors in M1.After the optimization, reservoir pressure increased greatly, and oil production increased 135% 6 months later comparing with that of the lowest period.This was very helpful for the uncompleted well pattern overseas, and of course would guide adjustments in the similar development status.