Block X has the characteristics of low porosity, low permeability and reservoir sensitivity. In the production process, it is easy to have problems such as rapid increase of water injection pressure, low water injection efficiency and rapid decline of production. In addition, due to the high water injection pressure of the reservoir itself, most of the water injection treatment technology will be greatly hindered. Therefore, based on the problem of pressurization and under injection of water injection wells in X block, in this paper indoor physical experiments were carried out, evaluates the ability of depressurization and injection increase under different fluids and different treatment radii, and clarifies the change law of pressure drop. Through the physical simulation experiment, the outcrop core displacement experiment was carried out by using the high temperature and high pressure displacement experimental device. The pressure drop variation law and effective driving distance under different conditions of low permeability reservoir were given, and the injection medium and injection mode were screened to provide data support for the optimization of depressurization fluid medium. This paper innovatively proposes to establish a model of reservoir injection measures. The indoor experiment evaluates the variation law of core displacement pressure drop of no less than 6 kinds of fluids under the conditions of 3 kinds of treatment radius, and gives the optimal parameter combination. The results show that the retarded acid + fracturing measures are most suitable for X block to reduce the injection pressure. The experimental results have important guiding significance for the selection of correct depressurization and injection technology in the process of oilfield exploitation, the necessary technical protection of the reservoir, and the realization of the comprehensive operation ability of low permeability oilfield.