Abstract: Method of numerical analog is discussed.A set of equations is worked out considering the thickness,heterogeneity,temperature and rock mechanics of the reservoirs,and integrating filtration mechanics with rock mechanics.Despite the complicate nature of the equations,non-linearity of unknown functions and presence of unknown boundaries(fractures),the finite element method for alternating solutions has been applied with success and satisfactory results obtained in calculation.Also discussed are the opening of fractures in reservoirs nearby the bottom of injection wells,size of fractures,contribution of fractures to the absorbability of reservoirs and interferences between the multi-fractured zones etc.in respect to the application of the method in sandstone reservoirs under high-pressure water flooding.Clarification of all these problems may help determine a reasonable range of water-flooding pressure.