Abstract: The flight environment and airframe configuration of high-speed aircraft are quite different from those of traditional flight vehicles, and there are many new problems in the study of their dynamic stability. In order to investigate the rolling stability of high-speed aircraft, a scaled model of typical high-speed aircraft with a through-flow inlet is designed, and the dynamic test technique of high-speed aircraft is developed. Through free rolling and forced pitching/free rolling dynamic tests, influence of the inlet opening/closing and the pitching motion frequency on the rolling stability is obtained, and the instability mechanism of forced pitching/free rolling coupling motion is discussed, with a comparative analysis using the aerodynamic/kinematic coupling numerical simulation method. The results show that the model with an open inlet has single-degree-of-freedom rolling stability, while the inlet closure will lead to a decrease in the rolling stability of the model at 10° angles of attack, resulting in rolling instability. Under the forced pitching/free rolling condition, as the pitching frequency increases, instability phenomenon such as single periodic attractors, double periodic attractors, and even irregular roll divergence appear during the rolling motion, indicating that forced pitching motions can lead to a decrease in the dynamic stability of the rolling channel. Numerical simulation results of the forced pitching/free rolling test show similar motion patterns to the dynamic test results, preliminarily verifying the effectiveness of the aerodynamic/kinematic coupling numerical simulation method.