The invention discloses a tool and a method for measuring the
deflection angle of an
airplane control surface. The measuring tool comprises a control surface clip (1), a stabilizer clip (6), a brace rod (5), a regulating arm (4), a sensor support (3), an
angular displacement sensor (7) and a forked
rocker arm (2). The measuring process comprises the following steps: clamping the stabilizer clip (6) of the measuring tool to a force-bearing position of a vertical
tail stabilizer (45), sequentially mounting the brace rod (5), the regulating arm (4), the sensor support (3), the
angular displacement sensor (7) and the forked
rocker arm (2) in place, clamping the control surface clip (1) to a force-bearing position of an upper
rudder (46), and moving the
angular displacement sensor (7) to a rotary shaft of the upper
rudder (46) so as to measure the
deflection angle of the control surface. The invention can be simultaneously used for measuring the
deflection angle of the
rudder or the
elevator in the
bench test or the ground built-in test of an
airplane, can be directly used for measuring the deflection angle of the control surface without disassembling structural parts of the
airframe, and is especially suitable for the condition that the deflection amount can not be educed for measurement by means of a link mechanism in case that the rotary shaft is arranged inside the envelope of the control surface.