The indexes to measure of the stiffness of the bridge including deflection, cycle stability factor and anti-push rigidity were summed up, and applicable premise of each index was analyzed. Taking an actual continuous rigid frame bridge as an example, five different calculation models were established to analyze the stiffness. The results show that the horizontal tie beam has no effect on the static stiffness,but on the period significantly; The stability of high pier continuous rigid bridges depends on the stiffness of the pier, with the increasing number of tie beams, the stability factor increasing, while the anti-push pier stiffness also increases, which is contradictory to demand of slenderness of piers. A reasonable cross-tie beam settings should be considered in the design.