Abstract: The burial depth in Shanshan extra-low permeabile Oilfield was 3 000 meters, Jurassic Sanjianfang reservoir is the main oil pay and the Physical properties of the reservoir is not good and has the character of non-Darcy flow. For raised the injection threshold pressure in the high water-cut stage, it is difficult to form the effective displacement field, furthermore the capacity of supply fluid is coming down in the reservoir and the difference among the reservoir beds is the experiential expressions of the hydraulic fracturing the becoming serious. Using the Poisson's ratio and breakdown pressure radius was studied and the least of increase pressure was demonstrated through the way of the abnormal fracturing pressure and the effective pressure gradient; confirmed the optimal water intake per unit thickness and formed the logical pressure that can make the effective displacement pressure gradient through the theoretic calculation, the well test analysis and field test. After increasing pressure, the water intake per unit thickness was become better and the fluid of the oil well was enhanced in great degree. It can provide reference for the same oil field in the late development stage and perfect the matched techniques of the water injection stage in the extra-low permeability oil field.