The invention discloses a method for measuring control dynamic shearing strain in a fatigue dynamic tri-axial test. The method comprises the following steps of: (1) charging a soil sample and draining and solidifying the soil sample; (2) closing a drain valve and applying vertical static stress and corresponding vertical dynamic stress in turn, wherein the cycle index of the vertical dynamic stress is more than or equal to 10,000; (3) recording the total vertical dynamic strain corresponding to each cycle index under the action of the vertical dynamic stress; (4) unloading the vertical dynamic stress so as to recover the structure of the soil sample; (5) correspondingly changing the magnitudes of the vertical static stress and the vertical dynamic stress, repeating the steps (2) to (4) and measuring and recording the total vertical dynamic strain corresponding to each cycle index under the actions of different vertical dynamic stress and vertical static stress; and (6) calculating a dynamic modulus and drawing relation curves between the dynamic modulus corresponding to different vertical dynamic stress and the cycle index under the same coordinate system so as to calculate the control dynamic shearing strain of the soil sample according to each curve. The method is simple and fast and has low cost.