The invention discloses a hydraulically controlled pivot type water injection pump capable of achieving automatic hydraulic pressure adjustment. The water injection pump comprises a front pressurization cylinder, a reversing working cylinder, a low pressure working cylinder and a back pressurization cylinder which are sequentially connected from front to back, wherein the front pressurization cylinder, the reversing working cylinder, the low pressure working cylinder and the back pressurization cylinder are connected to a main reversing valve through respective manifolds; the reversing working cylinder is connected with a pivot valve control manifold; the pivot valve control manifold is connected with the main reversing valve; the main reversing valve is further connected with a high-low pressure manifold through a self high-low pressure outlet; a front check valve group is arranged on the manifold connected between the front pressurization cylinder and the main reversing valve; a back check valve group is arranged on the manifold connected between the back pressurization cylinder and the main reversing valve; and the front check valve group communicates with the back check valve group. According to the water injection pump, surplus energy of a low pressure injection well is converted into energy required by pressurization injection of a high pressure injection well, energy does not need to be additionally added, water injection pressure of the high pressure well and the low pressure well is re-distributed according to needs, the injection pressure requirements of the high pressure well and the low pressure well are met, and the water injection pump has important meaning for decreasing the number of insufficient injection wells and improving the energy-saving effect of a water injection system.