The influence of gravity on water injection development of high dip reservoir cannot be ignored. Therefore, based on the establishment of mechanism models of different permeability and formation dip, the influence of formation dip and permeability on gravity is studied by analyzing the upward and downward flow law of injected water during water injection at the edge and top of high steep fault block reservoir. The result shows that when the permeability exceeds 10 mD and formation dip exceeds 5°, gravitation obviously becomes strong and water phase gravitation flow obviously heightens. With formation dip and permeability becomes higher, the downward flow rate of injected water dashes seriously, so water injection mode optimization and the ultimate recovery ratio in high and steep fault-block must be considered the gravity. The actual three-dimensional geological model in Block A and B in Tamsag Basinis is built. On the basis of thinking of gravitation, edge water-injection and edge combined point water-injection is determined by the numerical reservoir simulation. The prognostic chart of ultimate recovery is drawn for the edge water-flooding development reservoir, and matched in Block C and D, the similar oilfield development is given reference for the guidance.