Due to some problems in design or construction, some bridges may not be aerodynamically stable under the effects of wind. Usually, studies focus on installing damping devices in both passive and active control directions to improve the aerodynamic stability of bridge decks. In this paper, another solution is presented, which is to increase the torsional stiffness of the bridge decks. The complex eigenvalue method is used to calculate the critical flutter wind speed corresponding to the change of torsional stiffness. The calculation cases are applied to some famous bridges in the world with reliable data sets. Numerical simulation results show that this is a feasible method, bringing high efficiency to all calculated bridge cases without installing damping devices. In addition, the results also indicate that torsional stiffness plays an important role in the flutter stability. This is also a new research direction that can be carried out in subsequent studies.