Abstract: To make clear the value range of the central tower stiffness of the triple-tower suspension bridge, with the anti-skid safety factor and the deflection-to-span ratio of the main cable as the control indexes, the expressions for the upper and lower limits of middle tower stiffness of the triple-tower suspension bridges were deduced, so as to obtain the analytical algorithm for an appropriate stiffness of the middle tower. The formulas were verified by finite element models and the results showed good agreement. The formulas can be used to quickly select the type of middle tower for a multi-span suspension bridge at the initial design phase. Effects of major design parameters on the stiffness value of the middle tower were also studied. The research shows that the ratio of the dead load and the live load impose a significant effect on the tower stiffness value, and only when the ratio of the dead load and the live load is greater than 6.5, the middle tower stiffness can simultaneously meet the requirements of structural deformation and skid resistance of the cable. Effect of sag-to-span ratio to the middle tower stiffness depends on the ratio of the dead load and the live load. With the increment of span length, the value range of the middle tower stiffness increases.