The invention relates to a multi-stage gradient pressure-stabilizing drilling water pressure test device and method. The device comprises a water supply system, a multi-stage pressure-stabilizing system, a data collecting system and a drilling closing system, wherein the water supply system is composed of a water storage tank, a water pressure pump, a high-pressure soft pipe, a one-way valve and adrill pipe; the multi-stage pressure-stabilizing system is composed of a pressure-stabilizing room, three tees, three control valves, three pressure release valve of required gradient pressure and awater return pipe; the data collecting system is composed of a flow sensor, a seepage pressure sensor and a DT data acquisition instrument; the drilling closing system is composed of a power supply box, a water injection pump, two control valves, an upper rubber water stop plug, a lower rubber water stop plug, a high-pressure measurement soft pipe and a pressure meter. By means of the device, theproblem that an existing water pressure test device cannot precisely control the water pressure can be solved, it can be achieved that the flow rate and the seepage pressure can be collected in real time in the drilling water pressure process, and the water pressure testing efficiency and quality are effectively improved.