Abstract: The full-scale fatigue test of a certain type of aircraft slat belongs to structural fatigue airworthiness verification test. The main purpose of the test is to expose the fatigue weak parts of the slat structure, and verify whether the slat can meet the relevant requirements of widespread fatigue damage（WFD）. Besides, the test can provide test basis for the structural design, the improvement of manufacturing process, the formulation of limit of validity（LOV） for aircraft structure and structural change parts of related WFD structures. The follow-up loading technology is adopted in the test to simulate the actual state and loading condition, and ensure the accuracy of the loading under different configurations, so the opening angle of the slat surface will vary with the change of load spectrum. Finally, the follow-up loading of slat is realized. In the paper, a follow-up loading method is proposed according to the test requirements, and a follow-up loading mechanism is designed. In the process of slat retraction, by controlling the follow-up loading mechanism, the fixed point of the loading actuator moves synchronously with the loading point of slat, so as to realize the synchronous coordination of the wing deflection, the loading point position and the loading force, and finally realize the follow-up loading of the slat load.