Abstract: In the Upper ES2+3 oil Reservoir,south of Pucheng oilfield, oil layers are thick and heterogeneous, sweep efficiency of injection water is low,producing reserves of waterflooding are small,and production decline is sharp.Based on these charaderistics,this paper points out that the directiou of production potential tapping is increasing producing opere of waterfiooding, improving development effectiveness and realizing stable production, and that measures to tap production potential are performing whole tract profile control with PI decision-making technique. Field application of this technique in this reservoir was very successful.