In order to ensure the accuracy of weight deduction for large-deformation structure tests, a heavy-deformation structure strength test deduction technology was proposed, and a pulley block loading system deduction device was designed, which could realize the precise deduction of the structural weight during the test state and during the non-test period. The pulley block was composed of a movable pulley and a fixed pulley to ensure that the deduction device always remains horizontal under large structural deformations, ensuring the direction of the force line of the deduction load; the force control actuator effectively overcomes the influence of the friction force of the pulley block to ensure deduction under large deformation. Taking the static strength test of a certain type of aircraft spoiler as the research object, in the test, a brand-new test deduction method was used, and the test was successfully completed. The test results meet the test requirements and the feasibility and effectiveness of the buckle method is verified.