Abstract: In order to study the characteristics of strong coupling with multiple degrees of freedom of advanced layout fighters during post stall maneuver at high angle-of-attack, AVIC Aerodynamics Research Institute developed a three-degree-of-freedom large amplitude oscillation test system in the FL−51 low-speed opening wind tunnel. The system is mainly composed of a three-degree-of-freedom oscillation device, a hydraulic power unit and a drive control unit. The servo hydraulic swing motor and the high-precision micro servo motor are used as the driving elements of the movement, which can realize the single-degree-of-freedom, two-degree-of-freedom and three-degree-of-freedom large amplitude oscillation experiments of a 1 m magnitude model in the range of wind speed 20～60 m/s. The three-degree-of-freedom （roll, yaw, and pitch） large amplitude oscillation test was first realized in China with the small aspect ratio flying wing standard model. The results show that the test data obtained by the system is reasonable, and the performance indicators meet the requirements of the multi-degree-of-freedom coupled motion test in the process of aircraft development. The system can firmly support the model and has good structural stability.