Abstract: Flutter stability is a critical indicator of wind resistance in long-span bridges and presents a significant technical challenge in the design and construction of ultra-long-span bridges. Inspired by offshore engineering, this study investigates the use of anti-overturning and self-stabilizing characteristics of gyroscopic stabilizers to suppress bridge flutter, and proposes a time-domain analysis method for the bridge-gyroscope coupling system. Taking the Great Belt East Bridge as a project background, the motion equations of a biaxial gyroscopic stabilizer under small deflections were derived based on a three-dimensional coordinate system. The flutter derivatives were fitted using rational functions to obtain the time-domain self-excited forces associated with bridge flutter. This led to the development of a mathematical model for flutter analysis that incorporates the gyroscopic stabilizer. With the stabilizer mass set to be 0.06% of the equivalent mass of the bridge, a time-domain analysis of the bridge-gyroscope coupling system was conducted. The results indicate that the stabilizer's effectiveness in suppressing vibrations in the main beam's bending-torsion mode increases with rotational speeds. Time-history analysis reveals that with the increase of gyroscope speeds, the displacement of the main beam shows a decaying trend near the original flutter critical wind speed, thereby significantly improving the system stability and increasing the flutter frequency. At 3000 RPM, the system's flutter critical wind speed increases by approximately 50.1%, while the flutter frequency rises by 26.8%. It is demonstrated through complex modal analysis that the gyroscopic stabilizer controls flutter by enhancing the system's torsional stiffness.