The invention relates to a device and method for measuring high pressure leakage of a throttle orifice plate. The bottom face of a cavity of a test orifice plate seat in the device is machined according to the specification of an orifice plate seat face on a fuel injector body; the throttle orifice plate is placed in the cavity and pressed tight through clamping blocks, a contact face is formed between the lower surface of the throttle orifice plate and the bottom face of the cavity, and an oil return cavity is formed between the peripheral side face of the throttle orifice plate and the inner circumferential side face of the cavity; the inner end of a test oil inlet way communicates with one end of an oil inlet throttle hole in an aligning mode, and the outer end of the test oil inlet way is connected with a test pipeline; a communicating cavity is simultaneously in communication with the other end of the oil inlet throttle hole and the lower end of a central oil hole; the upper end of the central oil hole is connected to an oil tank through a first connecting pipeline, and a first flowmeter is installed on the first connecting pipeline; the inner end of an oil drainage way communicates with the oil return cavity, the outer end of the oil drainage way is connected to the oil tank through a second connecting pipeline, and a second flowmeter is installed on the second connecting pipeline; and a valve is arranged in the oil inlet throttle hole. According to the device and method for measuring high pressure leakage of the throttle orifice plate, a leakproofness test can be independently conducted on the high pressure sealing face of the throttle orifice plate, the test process is simple and flexible, and the test result is accurate and reliable.