Abstract: Based on structural finite element model, a 3-D approach for flutter analysis of long-span cable-supported bridges is presented. For this approach, the influences of static wind action, added attack angle of deck, self-excitation force and modes participation of cables can be taken into account, and the lateral, vertical as well as torsional frequencies can be iteratively searched simultaneously. Flutter analysis of Sutong bridge is conducted using this approach, and its reliability and practicability are testified. The analytical results reveal that: the critical flutter speed will be overestimated if the static wind action and the added attack angle of deck are omitted. If the self-excitation forces and modes participation of cables are not in consideration, the positive aerodynamic damping is equivalent to be omitted, and the critical flutter speed will be underestimated. For critical flutter speed, there are differences between the computational results obtained through flutter analysis and experimental ones measured directly in wind tunnel tests.